Malaysian maritime authorities say a fuel tanker was apparently hijacked and taken into Indonesian waters.

Malaysian Maritime Enforcement Agency chief Ahmad Puzi Kahar said Wednesday that “internal problems” led to the hijacking of the Indonesian registered MT Vier Harmoni.

He said the vessel was carrying about 900,000 liters of diesel and is now in waters off the Indonesian island of Batam, which is close to Singapore.

The Vier Harmoni is about 53 meters (175 feet) in length and was built in 2014, according to ship databases.