A ship full of rotting fish, with no crew or life-rafts, has been found drifting off the remote north-west coast of Australia.

Dubbed the "ghost ship", the 20-metre (65-foot) vessel, registered in Taiwan and flying an Indonesian flag, was boarded by the Australian navy last week after it was spotted drifting aimlessly.

It's certainly puzzled everyone Australian Federal Police spokeswoman

A massive search has turned up no clues, but the presence of up to three tons of rotting mackerel in the ship's hold has convinced police the boat was used by fishermen rather than people smugglers.

An international investigation is now under way to track down the owners of the boat.

Life-raft launched

The vessel, named the High Aim 6, was initially spotted at the beginning of January 100 kilometres (60 miles) off the north-west port of Broome.

The only occupants of the boat were tons of rotting mackerel

When the Australian navy boarded the ship they found the crew had gone, but many of their personal items, including seven toothbrushes, were still on the ship.

There were also signs that a life-raft had been launched.

The ship has now been towed into Broome, where it is being examined by Australian customs officials and police.

The reason for the ship's abandonment has mystified the authorities.

A spokeswoman for the Australian Federal Police admitted: "It's certainly puzzled everyone.

"The ship would require a crew of up to 12, it is in really good condition, and weather conditions in the area have been good since the vessel was first spotted."

There have been suggestions that the boat was used for illegal fishing, but police operations co-ordinator Bill Graham said he was keeping an open mind.

"At this stage we have not located the crew or discovered any plausible reason for their absence," he said.

The prime concern at this stage was to identify the crew members and determine if they were safe, Mr Graham said.