Washington: The United States and Israel have launched a diplomatic effort to prevent other countries from helping rearm Hezbollah, warning that a resumption of the weapons flow could ignite new fighting in Lebanon just as the ceasefire begins to take hold.

Officials have been pressing major world arms suppliers notably Russia and China not to allow their weaponry to find its way to the Lebanese group. They also have been urging Turkish officials to prevent any flow of weapons across their land or airspace.

Israeli officials, who were jolted by the sophistication of Hezbollah's missiles during the 34-day war, fear that the rearmament of Hezbollah could put them face to face in the future with weapons with an even greater capability to reach into Israel and to overcome its defences.

Israeli officials have made clear that they would try to destroy any shipment they detect, although such an attack probably would bring a Hezbollah retaliation and set off new fighting.

"We're very concerned about this issue," one Israeli official said in an interview. "It's the most urgent one on the table right now."

US officials contend that UN members are obligated to do what they can to block arms traffic to Hezbollah under the UN Security Council resolution adopted last week.

During the fighting, Hezbollah used sophisticated anti-tank weapons not only to destroy Israeli armour, but also as anti-personnel weapons. According to Israeli estimates, nearly half of the 118 Israeli soldiers who died in the conflict were killed by such weapons.

Hezbollah also fired advanced Chinese-designed C-802 anti-ship cruise missiles at an Israeli warship on July 14.

One of the missiles damaged the ship and killed four Israeli sailors.

Israel was able to disable a portion of Hezbollah's long range missiles in the opening hours of the conflict. But Israeli officials fear that if there is renewed fighting, Hezbollah will be better prepared.

Israel has been hoping that the new multinational force now forming for duty in Lebanon will be able to block arms shipments through the Lebanon's borders, airports and ports. But unresolved discussions at the United Nations about the force's duties have left unclear how active a role the force actually will have in guarding those entry points.

One UN official said early this week that the force will not take a direct role, but will act only as an adviser at the border crossings.

David Schenker, a former top Pentagon policy aide on issues pertaining to Arabic countries, said attempts to halt the arms flow will face difficulties, both in persuading the top arms suppliers to exercise restraint, and in restricting traffic at the Lebanese border.

He said both Russia and China have been inconsistent in their support of such efforts in the past. Now, with China eager to maintain its close relationship with Iran, a key oil supplier, hopes of convincing Beijing to bar weapons transfers "is a long shot at best".

Schenker, now a senior fellow at the Washington Institute for Near East Policy, said he is sceptical that the UN force will have the manpower or the skills to halt the arms flow at the Lebanese border. But he said the Lebanese government could turn to independent international "third party monitors," an idea that has been used in the past by Jordan and Indonesia to watch the passage of banned goods through their borders.

Schenker agreed that Israel unquestionably has a huge stake in halting the rearming. He said Israel might have destroyed as much as three-quarters of Hezbollah's rockets and missiles in the fighting.

But if Hezbollah is able to restore its arsenal, "this whole campaign may have been for naught," he said.