The sources added that top Iraqi Embassy officials are aware of the plot. Embassy officials were not immediately available for comment.
The sources said they had no information about any possible targets but that security has been stepped up at the US Embassy in Manila and other areas considered as possible "soft" targets in the metropolis.
"Just in case, we are taking precautionary measures. And units in the possible areas of concern have been alerted on the possibility of any terror attack," said one source, who spoke on condition of anonymity.
The MILF reportedly has ties with the al-Qaeda terrorist network of Osama bin Laden, a charge denied by the rebels.
The estimated 12,000-strong MILF, which has been holding peace talks with the government, has been fighting for an independent Islamic state in Mindanao since the 1970s.
Foreign Affairs Secretary Blas Ople said the government is confident that security forces will be able to meet any possible terrorist threat because the Philippines does not have a predominant Muslim population.
"There will be a threat of protests and demonstrations in Asean (Association of Southeast Asian Nations) countries with a majority Muslim population such as Malaysia and Indonesia," Ople said in a recent interview with British broadcaster BBC.
"Unlike in Indonesia, where almost 100 percent of their population is Islamic, we do not anticipate the social combustion that can happen elsewhere in the Philippines," he said.
Washington had earlier warned that al-Qaeda operatives might strike in the United States or in other countries if it goes to war against Iraq.
Earlier, the Communist Party of the Philippines (CPP) also threatened to launch "sympathy" attacks through its armed wing, the New People’s Army (NPA), if Washington carries out its threat to take military action against Baghdad for reportedly possessing chemical and biological weapons.
The CPP and the NPA are considered terrorist organizations by the United States and some Western European governments.
Ople said Asean foreign ministers will hold an emergency meeting in Phnom Penh if war breaks out in Iraq to come up with measures to protect their respective nationals in the Middle East who might be at risk.
"There are about 1.5 million Filipino workers in that region, more than 100,000 Thais and about the same number of Indonesians. So in the event of war in Iraq, we will coordinate our relocation, immigration measures among Asean countries," he said.
Last Feb. 2, President Arroyo flew to Kuwait to inspect evacuation plans for 60,000 Filipinos working there who might be at risk if war erupts in neighboring Iraq.
She will meet with Asean heads of state on the sidelines of the Feb. 20-25 summit of the Non-Aligned Movement in Kuala Lumpur to discuss measures on combating the regional terrorist threat.
Military and police officials, meanwhile, downplayed the CPP’s threat.
"We are ready for any event," said Deputy Director Gen. Reynaldo Velasco, Metro Manila police chief, adding that he has ordered tighter security across the metropolis.
Last week, police set up checkpoints to curb gun-related crimes and attacks by communist rebels following the recent assassination of former NPA chieftain Romulo Kintanar by a suspected rebel hit squad.
Although officials dismiss the NPA as a spent force, Velasco said they are not taking the CPP’s threat lightly.
"We are prepared for them," he said. "Our security measures have been in place since late last year. They were already proven effective so we only have to fine-tune some minor defects to make it more cohesive and adaptable to the present situation." – With Aurea Calica, Non Alquitran