The Philippines has said it is looking into reports that four Malaysians have been abducted off the coast close to southern Philippines. The area is usually frequented by the Islamic State (Isis)-linked Abu Sayyaf militant group, which is known for its extortion techniques.

The abductees were thought to be first kidnapped off the Malaysian coast before being brought to the southern Philippine archipelago of Sulu. Local police officers, cited by the Philippine daily ABS-CBN news, said the unidentified suspects brought the captives to the Sulu province. The army unit in the area has also been pressed into action.

Waters off the Malaysian coast and in the southern Philippines are commonly considered as havens of the Philippine Islamist organisation, Abu Sayyaf. The group, which recently executed two Canadian hostages after the country refused to pay a ransom, has stepped up their kidnappings in the past few months.

In April, Abu Sayyaf abducted four victims from the Malaysian island of Borneo. They were released in early June after their families raised funds for ransom with the help of other nations. In March, the group had also hijacked an Indonesian ship and taken all the 10 crew members as hostages and freed them later.

Abu Sayyaf is a hardline Islamist militant group, which is also linked to al-Qaeda, largely operating from the southern areas of the Philippines and remains a serious security threat to the Manila administration.