The southern Philippines has a long history of conflict, with armed groups including Muslim separatists, communists, clan militias and criminal groups all active in the area. The BBC News website looks at the main rebel factions.
Click on the links below for more on each group.
Moro National Liberation Front
Followers of Islam - called Moros or Moors by the Spanish - make up a sizeable population of the region.
The Moro National Liberation Front first appeared in the early 1970s, fighting for an independent Moro nation.
The group signed a peace agreement with the Manila government in 1976, but this failed to stick.
Another agreement, signed in 1996, gave predominantly Muslim areas a degree of self-rule, setting up the Autonomous Region in Muslim Mindanao (ARMM).
The ARMM is composed of the mainland provinces of Maguindanao and Lanao del Sur, and the island provinces of Sulu, Tawi-Tawi and Basilan.
As part of the deal, the MNLF chairman and founder of the group, Nur Misuari, was installed as the new regional governor.
But his rule ended in violence in November 2001, when he led a failed uprising and was jailed. Another MNLF leader, Parouk Hussin, took over as ARMM governor in 2002.
In February 2005, supporters loyal to Misuari launched a series of attacks on army troops in Jolo, the largest of the Sulu islands.
The trigger for the violence was thought to be the launch of a huge military operation to target the armed Muslim group Abu Sayyaf - which is alleged to have ties with the Misuari faction.
Nur Misuari was finally reinstalled as MNLF head in 2007.
In August 2007, the group said it was behind an ambush on troops in Jolo which led to nearly 60 deaths.
But the MNLF has become weaker over the years, and many factions have splintered from the main group.
Moro Islamic Liberation Front
The Moro Islamic Liberation Front is a more militant rebel group, which split from the MNLF in 1977.
It has a long-term aim of creating a separate Islamic state in the southern Philippines, but analysts say the group may well settle for a certain degree of Muslim autonomy.
The MILF puts more emphasis on its Islamic roots than the MNLF. Many of its senior figures are clerics.
Based in central Mindanao, the MILF has broad popular support in rural areas, where the lack of economic development has encouraged dissent.
The MILF have had on-off peace talks with the government for years
The group was subject to a crackdown in 2000 under the army of then-president Joseph Estrada.
But the mood turned when Mr Estrada was deposed amid popular protests in 2001, and Gloria Arroyo took power.
Talks between Manila and the rebels were revived, although they stumbled to a halt a couple of years later when the group was accused of harbouring a gang accused of kidnapping foreigners.
The MILF was also accused of being behind a bomb blast at Davao City airport in March 2003 which killed 21 people - and multiple murder charges were filed against the group's founder and then leader, Salamat Hashim.
A ceasefire was agreed later in 2003, but skirmishes continued.
In July 2007, MILF fighters were involved in clashes on Basilan island that left 14 Philippine troops dead, 10 of them reportedly beheaded.
In November 2007, the Philippines government said it had reached an agreement with the MILF on the boundaries for a Muslim homeland.
The Memorandum of Agreement on Ancestral Domain, a product of 11 years' negotiation, was ready for signing in Kuala Lumpur by August 2008.
This was intended as a roadmap toward a comprehensive final peace treaty.
It acknowledged the Muslims of Mindanao, or Bangsamoro, as a First Nation and laid the groundwork for creating a designated homeland. It also defined an area of ancestral domain.
But the geographical spread of this, and the breadth of opposition to President Arroyo, sparked protests from local officials who said they had not been fully consulted.
The Supreme Court ruled that the draft agreement was unconstitutional. President Arroyo then dismantled the negotiating panel and hinted that new talks would only be possible if the MILF first disarmed.
The failure of the negotiations prompted renewed fighting, which by mid-October 2008 had displaced 390,000 people, according to the International Crisis Group.
Negotiators from the government and the MILF met again in Kuala Lumpur in December 2009 and agreed that a peace deal could be signed by April 2010, before national elections in the Philippines in May.
The two sides agreed to revive an International Monitoring Team (IMT) of ceasefire observers and an ad hoc joint action group which would try to isolate Muslim militants from criminal groups in rebel-controlled areas.
Abu Sayyaf is the smallest and most radical of the Islamic separatist groups in the southern Philippines.
It is best-known for a series of kidnappings of Western nationals and Filipinos, for which it has received several large ransom payments.
In June 2002, US-trained Philippine commandos tried to rescue three hostages being held on Basilan island. Two of the hostages - one an American citizen - were killed in the resulting shootout.
The group has also claimed responsibility for a series of bomb attacks over the years - including an attack on a passenger ferry in Manila Bay in February 2004 that killed 100 people.
The army maintains a heavy presence in Mindanao
Abu Sayyaf's stated goal is an independent Islamic state in Mindanao and the Sulu islands, but the government views the rebels as little more than criminals, and refuses to hold any form of talks with them.
Abu Sayyaf - which means "Sword of God" in Arabic - split from the MNLF in 1991, under the leadership of Abdurajik Abubakar Janjalani, who was killed in a clash with Philippine police in December 1998.
His younger brother, Khadafi Janjalani, took over as leader, although he was killed by Philippine troops in September 2006.
Nationwide support for Abu Sayyaf is limited, but analysts say many locals in its stronghold areas of Jolo and Basilan tolerate the rebels and even work for them, attracted by the prospect of receiving lucrative ransom payments.
Both the MNLF and MILF have condemned the Abu Sayyaf's activities, and the US has included the group in its list of "terrorist" organisations, saying it has links with Osama Bin Laden's al-Qaeda network, although some analysts doubt this connection.
US troops have been helping the Philippine military fight Abu Sayyaf, although they are limited to a training and advisory position because the Philippine constitution bans foreign troops from taking part in actual combat.
Since launching a major operation in August 2006, Manila has claimed a series of successes - including the deaths of Janjalani and another senior Abu Sayyaf leader, Abu Sulaiman, also known as Jainal Antal Sali, in January 2007.
Reports in June 2007 said Abu Sayyaf had chosen Yasser Igasan, one of the group's founders, to succeed Janjalani as leader.
A popular Philippines TV presenter, Ces Drilon, her cameraman and a university professor were freed by kidnappers believed to be Abu Sayyaf militants, in June 2008, after more than a week of captivity on the island of Jolo.
In January 2009, gunmen abducted three staff members of the International Committee of the Red Cross - Swiss Andreas Notter, Italian Eugenio Vagni and Filipino Jean Lacaba - who are still being held more than two months later.
Philippine officials said in December 2009 that they had arrested an Abu Sayyaf founder - Abdul Basir Latip - who has allegedly been involved in kidnapping foreigners and Christians.
He has also been accused of forging links between Abu Sayyaf and other militant Islamist groups, such as Jemaah Islamiah and al-Qaeda.
Military chiefs believe Abu Sayyaf's numbers have now fallen to around 200, and they talk confidently of one day wiping out the rebel group entirely.
New People's Army
The New People's Army is the military wing of the Communist Party of the Philippines (CPP), and has been in existence for more than 30 years.
The group, which has bases on the island of Mindanao, has an estimated 10,000 members according to a presidential advisor on the peace process.
Peace talks between the CPP and the Philippine government stalled in June 2001, after the rebels admitted killing a Filipino congressman.
Many of the NPA's senior figures, including its founder Jose Maria Sison, live in self-imposed exile in the Netherlands, and claim to direct operations from there.
NPA supporters recently celebrated the group's 40th anniversary
In February 2004 a peace process was revived, with representatives of the NPA meeting government officials in the Norwegian capital Oslo.
The two sides agreed a series of measures to move towards a formal peace deal.
These included setting up a joint commission to examine human rights abuses on both sides, and working together for the removal of the NPA from the US and EU's list of terrorist organisations.
But little progress was made, and peace talks were suspended after rebels blamed the government for their inclusion on the US list of terrorist groups.
In August 2007, Jose Marie Sison was indicted in the Netherlands for ordering the murders of two former communist associates, Romulo Kintanar and Arturo Tabara, in 2003 and 2004, but the charges have since been dropped.
The CPP marked its 40th anniversary in December 2008 with a call to arms, outlining a strategy of confronting government and military officials, and their relatives and friends.
In an informal meeting brokered by Norway in the same month, rebel negotiators rejected an indefinite ceasefire pushed by the government as a condition for resuming formal talks.
No new meetings have been scheduled and in December 2009, the military said it raided a NPA camp in Bukidnon province in Mindanao, killing nine rebels for the loss of one soldier.