Uzi Mahnaimi in Tel Aviv, Timesonline

Three German-built Israeli submarines equipped with nuclear cruise missiles are to be deployed in the Gulf near the Iranian coastline.

The first has been sent in response to Israeli fears that ballistic missiles developed by Iran, Syria and Hezbollah, a political and military organisation in Lebanon, could hit sites in Israel, including air bases and missile launchers.

The submarines of Flotilla 7 — Dolphin, Tekuma and Leviathan — have visited the Gulf before. But the decision has now been taken to ensure a permanent presence of at least one of the vessels.

The flotilla’s commander, identified only as “Colonel O”, told an Israeli newspaper: “We are an underwater assault force. We’re operating deep and far, very far, from our borders.”

Each of the submarines has a crew of 35 to 50, commanded by a colonel capable of launching a nuclear cruise missile.

The vessels can remain at sea for about 50 days and stay submerged up to 1,150ft below the surface for at least a week. Some of the cruise missiles are equipped with the most advanced nuclear warheads in the Israeli arsenal.

The deployment is designed to act as a deterrent, gather intelligence and potentially to land Mossad agents. “We’re a solid base for collecting sensitive information, as we can stay for a long time in one place,” said a flotilla officer.

The submarines could be used if Iran continues its programme to produce a nuclear bomb. “The 1,500km range of the submarines’ cruise missiles can reach any target in Iran,” said a navy officer.

Apparently responding to the Israeli activity, an Iranian admiral said: “Anyone who wishes to do an evil act in the Persian Gulf will receive a forceful response from us.”

Israel’s urgent need to deter the Iran-Syria-Hezbollah alliance was demonstrated last month. Ehud Barak, the defence minister, was said to have shown President Barack Obama classified satellite images of a convoy of ballistic missiles leaving Syria on the way to Hezbollah in Lebanon.

Binyamin Netanyahu, the prime minister, will emphasise the danger to Obama in Washington this week.

Tel Aviv, Israel’s business and defence centre, remains the most threatened city in the world, said one expert. “There are more missiles per square foot targeting Tel Aviv than any other city,” he said.