Malaysia's police chief said on Tuesday that five-tugboat crew missing since last week were abducted by the Philippine militant group Abu Sayyaf, which is notorious for repeated kidnappings in waters between the two nations.
The five Malaysians were kidnapped from their vessel on July 18 off the coast of the Malaysian state of Sabah on Borneo island, Inspector-General of Police Khalid Abu Bakar told reporters.
"The five-tugboat crew have been kidnapped by the kidnap-for-ransom group from the southern Philippines," he said, confirming reports that had emerged over the past week.
The Abu Sayyaf, a loose network of Islamic militants that has earned millions of dollars from kidnappings in recent years, has been blamed for a recent burst of abductions.
In April and June, the group beheaded two Canadian tourists after ransom demands were not met, and a Malaysian man was beheaded last year.
In May, the Abu Sayyaf released 14 Indonesian sailors who had been kidnapped in two high-seas raids, attacks that prompted Indonesia, Malaysia, and the Philippines to launch joint patrols.
Formed in the 1990s, the Abu Sayyaf is a radical offshoot of a Muslim separatist insurgency in the south of the mainly Catholic Philippines.
Its leaders have pledged allegiance to the Islamic State group, but analysts say the Abu Sayyaf mainly focuses on lucrative kidnappings.
Eastern Sabah is just a short boat ride from islands of the southern Philippines where government authority is weak and banditry common.
Earlier in July, three Indonesians were kidnapped in the area, and in late June seven other Indonesians were taken.