MANILA - Twelve homemade bombs were found aboard a passenger ferry in the Philippines just before it left port with more than 300 passengers, the coast guard said Sunday.

The explosives were found in a trash can on the second deck of the MV Blue Water Princess in the port of Lucena City, 120 km south-east of Manila, Saturday.

Coast guard station commander Gregorio Adel Jr said the bombs - 12 bottles attached to electrical wirings and packed with nails and scrap metal - were hidden in a jute sack placed in the trash can.

Adel said bomb-sniffing dogs found the explosives while inspecting the ferry before its departure. Bomb experts removed the bombs and defused them.

He said the coast guard received information that the bombs were part of a destabilisation plot ahead of President Gloria Macapagal Arroyo’s key congressional speech Monday.

But Adel said authorities were still investigating if the bombing attempt could have been perpetrated by Islamic militants.

“We are still investigating the incident and checking which groups had the motive and capacity to conduct such an attack,” he said.

Earlier in the month, a spate of bombings struck the southern Philippines, killing 12 people and wounding 100 people. The attacks were blamed on Muslim separatist rebels.

Philippine security forces went on highest alert Sunday ahead of Arroyo’s ninth and supposedly last state of the nation address Monday.

Various groups are planning to hold massive street demonstrations to denounce Arroyo’s poor performance since 2001 and to remind her that she has to step down next year.

General Victor Ibrado, armed forces chief of staff, urged rallyists to help ensure safe and peaceful demonstrations.

“Our appeal is for them to just conduct their rallies peacefully as they say they would so we will not have a problem,” he said.

Ibrado said troops have been instructed to exercise maximum tolerance in dealing with the demonstrators, but stressed that they were allowed to take action if needed for their protection.