The US Coast Guard has opened fire to sink the Japanese “ghost ship” cast adrift by last year's massive tsunami, which was approaching the shores of Alaska.

The deserted ship, which was more than 60 meters long, posed a significant risk to marine traffic as it drifted through shipping lanes and at some point might have interfered with other ships.

The Coast Guard cutter, Anacapa, fired on the abandoned Ryou-Un Maru in the waters of the Gulf of Alaska more than 240 km from land, spokesman Paul Webb said.

An initial salvo of 25mm explosive rounds caused the ship to catch fire and begin to take on water, listing slightly, according to Coast Guard Chief Petty Officer Kip Wadlow.

A huge column of black smoke could be seen rising into the air.

A second salvo was fired later in the afternoon, he said.

In about four hours, the ship vanished into the water. A Coast Guard C-130 plane crew monitored the operation.