The Israel Navy intercepted an estimated 50 tons of weapons from Iran yesterday aboard a cargo ship bound for the Gaza Strip, including sophisticated land-to-sea missiles that could have enabled Palestinian militants to hit ships at Ashdod Port or at sea, or other Israeli targets like a crude oil depot or a gas drilling rig, the navy said.

The weapons were aboard the Liberian-flagged Victoria, which naval commandos took over in the Mediterranean Sea. The shipment is estimated to be as large as that captured by Israel in 2002 aboard the Karine A, which was also headed for the Palestinians.

The Chinese-made C-704 missiles were "undoubtedly strategic weapons" that could have posed a significant threat to Israel's coastal and marine infrastructure, said the navy's deputy commander, Brig. Gen. Rani Ben-Yehuda.

He said Iran is known to possess these weapons. The shipment also included instruction manuals in Farsi, and there were other clues that explicitly showed Iranian involvement, said Ben-Yehuda.

The military released a photo of a booklet with the words "technical missile identification document" written in Farsi on the cover. It identified the system as a C-704 Nasr missile, and provided a serial number and date of issue in the Persian calendar.

"This isn't just smuggling, but a state-supported undertaking whose central goal is to arm the terror organizations around us," Ben-Yehuda said. "We shouldn't be the only ones worried; the entire international community should be worried too. This is a cynical exploitation by Iran, which is smuggling weapons while endangering innocent civilians aboard the ship and at the ports where it docked."

The navy said at least two of the land-to-sea missiles, which have a range of 35 kilometers, were aboard the ship. The missiles weigh 360 kilograms each, making them relatively mobile.

Hezbollah has similar missiles, but the Palestinians do not.

The capture of the Iranian weapons shipment - the fourth in the past decade - is seen as a major success for the navy and the intelligence agencies.

Iran has recently significantly increased its aid to Gaza, and was apparently trying to replicate its previous success in Lebanon.

In July 2006, two days after the outbreak of the Second Lebanon War, Hezbollah fired a C-802 missile that hit the Israeli naval ship Hanit and nearly sunk it. The missile, an Iranian variation of a Chinese model, killed four sailors, and Hezbollah leader Hassan Nasrallah boasted that he had carried out his promise of "strategic surprise."

Later, analysts said Israeli intelligence officials had missed early signs indicating that Iran had provided Hezbollah with the missile.

In addition to the missiles, the weapons shipment also contained 60-millimeter and 120-millimeter mortar shells.

On its way from Egypt's Alexandria Port, the Victoria was asked to stop when it came within 200 miles west of the Israeli coast. The captain didn't resist and the crew put out a ladder for the Israeli commandos, Ben-Yehuda said.

"The activity was carried out under international law, which allows us to examine ships whose loads are suspicious," he said.

The commandos examined the loading documents and noticed that the ship had stopped in Beirut and Syria before reaching Turkey and Egypt. They opened three containers that were registered as containing lentils and cotton. Unusually for such a shipment, the containers were locked, and the commandos found weapons beneath the declared items.

Ben-Yehuda said neither the crew nor the Egyptian or Turkish governments appeared to know anything about the weapons shipment.

Israel's announcement that Turkey was not involved in the arms shipment appeared to be an effort to defuse any potential tensions with Ankara.

"We know that Iran is conducting an intensive and ongoing effort to smuggle in weaponry," said Ben-Yehuda. He said it was possible the weapons may have been delivered to the Syrian port of Latakia by Iranian military ships when they arrived there in late February.

He said Iran appears to have planned to use underground tunnels in Rafah to smuggle the weapons from Egypt to Sinai and from there to Gaza. Other military sources highlighted Syria's role in the weapons shipment, in coordination with Iran.

Turkey confirmed it was not involved and said many ships stop at its ports for refueling, loading or unloading materials. There was no immediate reaction from Hamas, Syria or Iran.

The Victoria is German-owned and operated by a French shipping company, the Israel Defense Forces said. German, French and Liberian authorities were notified of the seizure.

Although the ship was intercepted outside Israel's territorial waters, maritime law entitles Israel to search any merchant vessel it has reason to believe is carrying contraband to support Hamas, said Benjamin David, a former high-ranking officer in the military's legal department.

The operation was reminiscent of the November 2009 Israeli takeover of the Iranian Francop vessel off the coast of Cyprus. Israel captured hundreds of tons of rockets, missiles, mortars, grenades and anti-tank weapons on board that vessel, which it said were designated for Hezbollah guerrillas in Lebanon. In 2001 and 2002, Israel seized ships carrying tons of weapons it said were intended for Palestinian militants.