The Philippine government has warned that the threat from terrorist attacks on the capital Manila is not over despite the arrest last week of suspected Islamic militants.

Defense Secretary Eduardo Ermita told journalists that members of the militant Abu Sayyaf group may still be on the loose in Manila.

He says the Philippines is tightening security for the long Easter vacation that starts Wednesday, including posting armed secret marshals on planes, boats and buses.

Last week the government arrested six alleged members of the Islamic militant group, accusing them of plans to bomb shopping malls and railways in Manila. Other suspected militants were also detained.

The Islamic Abu Sayyaf, which has been blamed for bombings and kidnappings in the Philippines, is on the U.S. list of terrorist organizations and is linked to the Jemaah Islamiyah and al Qaida terror networks.

Ermita says intelligence reports show members of Jemaah Islamiyah, or JI, have trained members of the Abu Sayyaf in explosives. He says JI is supported in turn by a faction within the separatist Moro Islamic Liberation Front, or MILF, which is opposing peace talks with the government.

"We have information within the hierarchy of the MILF not everyone is in agreement about the peace process," he said. "There is a group that thinks? that they can still achieve their objective of putting up a Pan-Islamic state or an independent Islamic state through armed struggle."

Mr. Ermita adds that the MILF's mainstream leadership remains committed to fresh peace talks with the government later this month, aimed at ending the group's decades-old secessionist struggle.