Ten Malaysian fishermen were kidnapped by suspected Islamic State-linked militants off Borneo island on June 18 and were taken to the southern Philippines, local police said.
The gunmen attacked two boats off eastern Sabah state in the Malaysian part of Borneo. Ten people onboard were held hostage, while six other escaped.
Malaysia's official news agency Bernama cited the police as saying that Philippine kidnap-for-ransom gang Abu Sayyaf is thought to be responsible, and the fishermen were taken to islands in the south of the country.
Abu Sayyaf has operated in the southern Philippines since 1990s and is notorious for kidnappings of foreigners and bombings.
There has been a spate of kidnappings in the waters between the southern Philippines and the Malaysian part of Borneo in recent years.
In 2017, several Southeast Asian countries started naval patrols in the area to prevent kidnappings.
VNA