Crew members of a Japanese oil tanker might have conspired with the thieves in robbing the vessel of US$2.5 million worth of diesel fuel while traversing the Straits of Malacca near the Malaysian capital, police said today.

Abdul Rahim Abdullah, Federal Marine Police deputy commander, said it was highly suspicious that the crew members had not raised the alarm during the entire period of the robbery, which took between seven to eight hours.

“We are puzzled as to why they did not push the distress button,” he said. “We have not discounted an inside job.”

Investigators said eight armed men boarded the Japanese vessel Naniwa Maru 1 before dawn Tuesday. At the time it was located about 16 nautical miles off Pulau Kitam, in the state of Selangor, and was on its way to Myanmar.

Two other vessels berthed on both sides of Naniwa Maru 1 and siphoned off 3.2 million litres of its 5.3-million-litre diesel fuel cargo.

A maritime police source said investigators were scrutinising the background of the three crew members, who turned out to be the vessel’s captain, first engineer and chief mate, initially reported as kidnapped by the robbers.

“When we looked at their rooms, there were no personal belongings left there and their passports were also gone,” he said.

The crew members of the Naniwa Maru 1 are composed of 10 Indonesians, seven Thais and one Indian national.

Naniwa Maru 1 , with gross tonnage of 2,991 tonnes, is owned by Japan-based Naniwa Tanker company.

- dpa