BATAM (Jakarta Post/Asia News Network) - Indonesian maritime police have detained a Malaysian-flagged tanker off the Sumatran coast while it was transporting 800,000 kilolitres of diesel fuel to Singapore.

The vessel was allegedly transporting fuel from Palembang, South Sumatra, to Singapore without proper documents, a move which would cost 10 billion rupiah (S$1.02 million) in financial losses to Indonesia.

Security officers from the Riau Islands Police's water police unit (Polair) detained the vessel, MT Urban Success, on Friday, Riau Islands Police chief Arman Depari told The Jakarta Post on Sunday.

The captain of the 740-gross-tonne vessel, identified only as "YS", as well as all seven crew members had been taken into custody at the Polair headquarters for further questioning.

Arman said the MT Urban Success's arrest was the police's biggest sea arrest in the last two years.

"We had been spying on the vessel for two weeks before the arrest. This is the biggest fuel smuggling vessel we have busted in the last two years," said Arman.