Israeli naval commandos have boarded a ship carrying Iranian-supplied rockets destined for Lebanon's Hizbollah group and taken the vessel to an Israeli port, the government said yesterday.

Deputy Defence Minister Matan Vilnai told Army Radio that Katyusha rockets were found on the Antigua-flagged Francop, which the military said was intercepted overnight in the Mediterranean Sea, 160 kilometres from Israel. It was brought to Ashdod, south of Tel Aviv.

A Cyprus-based shipping source told Reuters the ship had been due to call in Lebanon.

"Stopping the Iranian weapons ship was an important achievement for the Israel Defence Forces and the state of Israel," President Shimon Peres said in a statement.

The 8,622 deadweight tonne ship was due to have arrived on November 1 at the Egyptian port of Damietta and was last seen on October 31 in the Mediterranean sea between Lebanon and Cyprus, according to AISLive ship tracking data on Reuters.

The vessel is owned by German shipping company Reederei Gerd Bartels, based near the port of Hamburg. Asked to comment, Mirko Bartels of the private shipping firm said: "We have nothing to say."

An official with Cyprus-based United Feeder Services said it had acted as the time charterer and carrier for the Francop, tasked with loading and discharging the vessel.

"The vessel sailed from Damietta, and was bound for Limassol, Cyprus and then Lebanon, Turkey and back to Damietta," the official, who declined to be named, said.

"We are not allowed to open up containers to see what is inside," he said. "We do not have much information. We just know that the vessel was seized and was forced to go to Ashdod to check the cargo."

Military sources said naval commandos seized the 137-metre-long vessel in international waters.

Asked if the weaponry on the ship had been earmarked for Hizbollah, Mr Vilnai said: "Yes. It strengthens (the group) and improves its long-range firing capability into Israel."