KUALA LUMPUR - A ship with 3,500 metric tonnes of marine fuel oil that was reported missing in the Malacca Strait off Malaysia on Saturday, has been found in Indonesian waters without its cargo, the Malaysian Maritime Enforcement Agency said.

The 10 crew members of the Singapore-registered tanker MT Joaquim, which had been on its way to Langkawi, Malaysia, from Tanjung Pinang, Indonesia, were released by a group of hijackers at 8.55am on Sunday, Reuters cited the agency as saying in a statement.

The tanker had gone off the radar at 9.35pm on Saturday, the New Straits Times newspaper reported.

The ship was later found near Indonesia's Rupat Island with its cargo missing, the agency's deputy director general of operations and Maritime Vice-Admiral, Ahmad Puzi Ab Kahar, said. He said the oil cargo was worth US$700,000 (S$969,000), the paper reported.

"A total of 15 ships, 9 boats and 4 aircrafts were immediately deployed to the search area at Malacca Straits, including assets from Singapore, Thailand and Indonesia," Puzi said, according to the paper.

The paper said there were 10 crew members on board the tanker - nine Indonesians and one Singaporean. All of the crew members were safe.

The Bernama news agency named the Singaporean crew member as Lim Puay Huang, 39. Lim is being treated at Hospital Melaka for a minor injury, it said.

Puzi said a "phantom ship" was believed to be involved in the incident. There was also a possibility that an "insider" was involved as the tanker had been heading north before changing course to a southern direction.

He added that investigations were ongoing.

On June 11, oil tanker MT Orkim Harmony, carrying 6,000 tonnes of petrol, was hijacked by pirates en route to Kuantan Port from Malacca. The ship with 22 crewmen were released unharmed before the pirates were caught in Vietnam waters.