Manila  - The Philippine government Wednesday warned against possible terrorist attacks while the predominantly Catholic country celebrates Christmas and urged the public to be vigilant.

Presidential Executive Secretary Eduardo Ermita said security forces had received information "a few months back" on plans by terrorist groups to launch attacks during the holidays.

He said the government had been preparing since then for possible terrorist attacks.

"We don't want to take chances, whether there is information or not, we are assuming there are people who want to create trouble."

Ermita said two bombings in the southern city of Iligan on December 18, which killed three people and injured more than 40, were believed to be part of the plot.

Two more unexploded bombs were later found in Iligan City.

"Without being alarmist, we are appealing to the public to be vigilant against terrorism," Ermita said. "We encourage everyone to closely watch out for those who might want to create trouble."

He said the groups behind the plot were the Abu Sayyaf, the Jemaah Islamiyah (JI) and a special operations group of the separatist Moro Islamic Liberation Front (MILF).

The plot involved bombings in urban centres in the southern region of Mindanao and Manila, Ermita said.

"Manila has always been in their target list," he said. "So we did target-hardening, that's why we have additional soldiers and police out in public places to protect the public."

The Abu Sayyaf and the JI have both been linked to the al-Qaeda terrorist network and have both been blamed for some of the worst terrorist attacks in the Philippines and South-East Asia.

The MILF, the largest Muslim rebel group fighting for a separate Islamic state in the southern Philippines, has denied being involved in terrorism.

But authorities alleged that some MILF commanders and breakaway units have tied up with Abu Sayyaf and JI militants to launch attacks and engage in criminal activities. (dpa)