Malaysian authorities are working to salvage a 45-year-old fast attack naval ship that sank after it struck an unknown underwater object.

The navy said in a statement that a leak was first detected in the engine room of the KD Pendekar on Sunday, which quickly flooded the vessel.

The crew failed to fix the hole and the 260-ton ship sank hours later off the coast of southern Johor state, it said.

All 39 crew members were evacuated safely, with no injuries.

“The leak is believed to be caused by the ship hitting an underwater object,” it said, adding that salvage operations were under way.

An investigation has been launched into the cause of the incident, it added.

On Monday, Defence Minister Mohamed Khaled Nordin ordered an inspection of navy vessels over 40 years old, which make up at least a third of the country’s fleet.

The Pendekar, built by Karlskrona Varvet Shipyard in Sweden, was commissioned into the Malaysian fleet in 1979.

“We do not deny that (some of) our ships are old but that is not likely to be one of the causes … and the important thing is that thankfully no lives were lost,” Mr Khaled was quoted by the Malay-language Harian Metro newspaper as saying.

The minister said a fleet modernisation is ongoing, involving the construction of littoral combat ships, with the first due to be commissioned in 2026. The ministry is also negotiating to purchase littoral missions ships from Turkey, he added.