Vidal Querol, Metropolitan Manila's police chief, said about 15 check points were set up around the capital to guard critical public and private installations such as petrol depots, power, water and communications stations and bus and train stations.

''We have been getting intelligence reports on an alleged plot by terrorist groups to plant bombs in Manila and other key urban centres in the south,'' Querol told journalists, adding he had met with mall owners to seek their help in tightening security.

''They promised to help us ensure the safety of shoppers by beefing up mall guards and installing extra security cameras.''

Querol said the nearly 20,000 police officers in Metropolitan Manila, the sprawling capital of the poor Southeast Asian state, were placed on heightened alert at dawn on Thursday.

''In the last few weeks, we're getting consistent reports from various sources about a plot by Muslim rebels to simultaneously bomb three or four targets in the capital,'' a senior police intelligence official told Reuters.

The official said authorities were worried because the reports filtering in contained ''very specific'' details about the bomb plot, such as date, time and place of targets.

Brigadier-General Delfin Bangit, commander of the elite Presidential Security Group, said they were concerned about the increasing threats from local militant groups with suspected ties to Indonesian jihadist groups.

''There were consistent reports of bombings,'' said Bangit.

''We are very concerned because the president has been moving around.''

Intelligence officials blame a small group of radical Muslim converts, Rajah Solaiman Revolutionary Movement, for the series of bombings in the capital since 2004, including the worst attack that killed over 100 people in a ferry explosion.

Two of the group's top leaders -- Ahmad Islam Santos and Pio de Vera -- were arrested last year in the southern port city of Zamboanga, disrupting an alleged plot to detonate a truck bomb in Manila.

''Our latest information suggested a fresh plot to be carried out by new recruits,'' the intelligence official said, adding the regional militant network Jemaah Islamiah and its local partner Abu Sayyaf may have provided funds for the planned attack.