KUALA LUMPUR, Malaysia (AP) — Pirates stopped a Singapore-owned tanker in the Malacca Strait and stole several million liters of diesel fuel it was carrying, Malaysian marine police said Wednesday.

Marine police deputy commander Abdul Rahim Abdullah said the tanker was sailing from Singapore to Myanmar when it was boarded by up to 10 pirates armed with pistols and machetes early Tuesday off Klang port.

Abdul Rahim said two other tankers appeared and an estimated 3 million liters, of the 5 million liters of diesel on board the vessel, were transferred over a span of several hours.

He said the ship's captain, chief engineer and a supporting crewmember — all Indonesians — were found missing along with their passports and belongings. Authorities are probing the possibility that the three may be involved in the robbery.

"We are doing a thorough investigation. We have ruled out kidnapping because no ransom demand has been made," he told the Associated Press.

The ship is now anchored at Klang port outside Kuala Lumpur for further investigations, he said.

Initial reports said it was a Japanese tanker but Abdul Rahim said the ship has been sold to a Singapore company.

The narrow Malacca Strait, shared by Indonesia, Malaysia and Singapore, is a major shipping route for oil as it is the shortest sea route between the Middle East and Asia. One-third of the world's shipping trade goes through it.

Piracy, mainly low-level thefts, had been declining following maritime patrols by the three countries, but attacks appeared to have picked up last year in Malaysian and Indonesian waters.