MANILA (Reuters) - Masked gunmen kidnapped two Indonesian fishermen in waters off eastern Malaysia and military units were on alert to intercept them as they headed towards the southern Philippines, the army said on Sunday.

Five men snatched the two fishermen late on Saturday from a Malaysian-registered fishing trawler off Sabah. The army suspects the incident could be the work of Abu Sayyaf rebels.

“The gunmen and their victims sped off towards the southern Philippines,” army spokesman, Major Filemon Tan, told reporters, adding ground and naval units were trying to intercept the assailants.

Abu Sayyaf operates in the Sulu Archipelago close to Malaysia and was founded with a separatist agenda, pledging allegiance to Islamic State and al-Qaeda.

But it is better known for its lucrative acts of banditry and piracy that have not abated, even as Philippine troops step up offensives to dismantle the network.

President Rodrigo Duterte discussed the maritime threat of Abu Sayyaf with Malaysian Prime Minister Najib Razak recently, agreeing to cooperate to stop the kidnapping.

Abu Sayyaf’s tactics are brutal, decapitating hostages when ransom demands are not met.

They are holding 22 captives, including a Dutch, a German, a South Korean, five Malaysians, two Indonesians, six Vietnamese and six Filipinos.