Police in the Philippines have arrested two men in connection with a series of bomb attacks in the southern city of Davao, President Gloria Arroyo said on Tuesday.
Ms Arroyo said the two men, named as Tutamed Urong and Toto, were arrested in Cotabato city, 880
kilometres (550 miles) south-east of Manila, after a joint army and police operation.
Military officials confirmed that both men were Filipinos.
Toto has been accused of planting last Wednesday's bomb, which killed 16 people and injured more than 50 others in Davao's busy wharf area, Ms Arroyo said.
Both men are also believed to have been involved in an explosion outside Davao's airport on 4 March, which killed 22
people and injured more than 100.
It is not known whether the two men have links with any militant organisation. Some officials have blamed the two attacks on the Moro Islamic Liberation Front (MILF), one of several groups fighting
for a separate Islamic state in the predominantly Christian Philippines.
Ms Arroyo also said there was "reliable intelligence" that Indonesian nationals were involved in the recent attacks.
She said she had asked military chief General Narciso Abaya to "work closely with the Indonesian Government", after police reports on Monday linked five Indonesians to last week's blast at Sasa wharf.
Philippine police intelligence chief Robert Delfin said the five were believed to be members of Jemaah Islamiah (JI), an militant Islamic group suspected of carrying out last October's Bali bombing.
Mr Delfin said that two of the five Indonesian suspects had been seen in the outskirts of Davao just before the attack.
Last week President Arroyo warned that Davao, which was largely a peaceful city before the two attacks, was now in a state of "lawless violence".
Davao is the largest city on the island of Mindanao, and has a mostly Christian population.
Mindanao is mired in factional fighting, with government troops clashing regularly with a series of Muslim separatist rebel groups.