JOLO, Sulu--(UPDATE) Marine soldiers have arrested three persons who were allegedly transporting hundreds of sacks of ammonium nitrate in Indanan town in Sulu.

Aside from the 283 sacks of ammonium nitrate, members of the Marine Battalion Landing Team 6 (MBLT 6) also confiscated at least 50 blasting caps -- materials used in making improvised explosives -- in a raid in Buansa Pier in Indanan on Saturday.

The sacks of chemicals were loaded on a boat. The blasting caps, a .45 pistol, ammunition and a handheld radio were recovered in a nearby house.

Ammonium nitrate is an agricultural chemical used in making fertilizer, but is also widely used by the Abu Sayyaf in making powerful explosives for random attacks in the south.

Maj. Gen. Juancho Sabban, commander of Task Force Comet, said they were checking possible Abu Sayaff involvement, adding that the raid was conducted near an Abu Sayyaf camp, which was overrun by government soldiers last April.

"With blasting caps and ammonium nitrate, which are the basic ingredients in the so-called fertilizer bombs, it is obviously meant for a terrorist action," Sabban said.

He said the suspects were being investigated and authorities were not ruling out the involvement of the Abu Sayyaf.

The Abu Sayyaf is a small gang of Islamic militants founded by Filipino Islamic firebrand Abubakar Abdurajak Janjalani after returning from Afghanistan, where he fought alongside Osama bin Laden's forces against the Soviets.

Janjalani was killed in a gunbattle with Philippine police in 1998 and the group subsequently became a criminal gang specializing in kidnappings, extortion and bombings.

The Abu Sayyaf group has kidnapped dozens of foreign tourists since 2000. It is wanted for the deaths of two American hostages they grabbed from a Philippine beach resort in 2001.

Small numbers of US forces have been training Filipino forces in the south over the past five years, leading to the arrest and killings of top Abu Sayyaf leaders.