Mr Siniora has a background in banking and finance
Fouad Siniora was the right-hand man in business and politics of the slain ex-premier Rafik al-Hariri for more than 20 years.
He served in all five Hariri cabinets from 1992 to 2004, first as minister of state then finance minister.
After Hariri's assassination in February 2005 and the success of the anti-Syrian 14 March forces in elections a few months later, Mr Siniora was backed as prime minister by Hariri's son and political heir Saad.
His term in office was dominated by the 2006 war between Israel and Hezbollah, followed by a dangerous standoff with the Hezbollah-led opposition.
The opposition withdrew their ministers from Mr Siniora's unity government in November 2006 in a bid to force him to resign.
On 13 November 2006, Mr Siniora rejected the resignation of all five Shia Muslim opposition ministers and a Christian ally. The ministers resigned after disagreements on the government's position from the endorsement of the international tribunal on the assassination of Rafik al-Hariri.
The resignation prompted the opposition and then Lebanese President Emile Lahoud to consider Mr Siniora's US-backed government to be "lacking constitutional legitimacy".
On 21 November 2006, the minister of industry, Pierre Gemayel, was assassinated in Beirut. Mr Siniora told the Saudi paper Ukaz that the assassination of Gemayel is "an attempt to topple the government and obstruct the international tribunal [investigating Hariri's death]".
In December 2006, the opposition began a sit-in in downtown Beirut to call for Mr Siniora's resignation. The 18-month sit-in ended after the signing of the Doha agreement between Lebanese rival groups on 21 May 2008, which stopped the worst fighting seen in Lebanon since the end of the civil war in 1990.
The clashes broke out when Hezbollah and the opposition said the decision of Mr Siniora's government on 6 May, to investigate Hezbollah's private telecommunications network and sack the head of airport security, was a "declaration of war".
Hezbollah was initially represented in Mr Siniora's government, which recognised "the resistance's" objective of liberating Lebanese occupied territories, mainly the Shebaa farms.
During the war with Israel, he told the Italian paper La Repubblica that "the Lebanese army is going to be the one dealing with Hezbollah and with its weapons".
Following the war, relations with Hezbollah soured. In December 2006, Mr Siniora accused Hezbollah leader Hassan Nasrallah of "trying to stage a coup".
The Lebanese news agency NNA quoted him as saying: "The current position of the government in defence of democracy and liberties in the country proves that no change can take place on the street or through a so-called coup.
"This would be a coup against the constitution and the democratic institutions. This government has held fast, based on the support of the Chamber of Deputies and the citizens."
Mr Siniora was born in 1943.
Like Mr Hariri, he grew up in the southern coastal city of Sidon in a Sunni Muslim family.
He attended the American School for Boys in Sidon and the American University of Beirut, where he gained an MBA. He speaks fluent English.
Mr Siniora's business career has been in banking and finance. He held a senior position in the Central Bank of Lebanon from 1977 to 1982.
He then joined Mr Hariri's growing business empire, running his financial interests. He is currently the chairman and managing director of Groupe Mediterranee - which encompasses four Hariri-owned banks.
During the 1970s he also lectured at the American University of Beirut and the Lebanese University.
His interests include a passion for Arab literature and writing poetry. He is married with three children.
Dealing with debt
As acting finance minister in 1995, he took steps to deal with a shortfall in the state budget, caused by servicing the country's debt and the public sector wage bill.
But his critics blamed him for exacerbating the problem, helping the country's debt balloon to its current figure of $35bn.
In 1998, when Mr Hariri was out of office, an inquiry was launched into allegations he had removed documents from the finance ministry - part of wider accusations of corruption and financial mismanagement.
He dismissed the rumours as "nothing but dust that will vanish in the end". The campaign against him is said to have been encouraged by Lebanese President Emile Lahoud.
In February 2000 he faced an investigation over claims he had allocated state funds for a waste recycling plant that was never built. He was cleared of all charges in 2003.
BBC Monitoringselects and translates news from radio, television, press, news agencies and the Internet from 150 countries in more than 70 languages. It is based in Caversham, UK, and has several bureaus abroad.