UNITED NATIONS (AFP) - Multiple diplomatic, political and logistical problems must be tackled before an international peacekeeping force can be sent to keep Israeli and Hezbollah forces apart.

Israel and Hezbollah each have conditions for accepting a force, the US reluctance to contribute troops could add a credibility problem and just agreeing a mandate at the United Nations will take time, diplomats and experts said.

Potential contributors have also been made wary by the death of four UN peacekeepers in an Israel shelling last week in south Lebanon.

The UN Security Council has yet to agree a resolution setting out details of a force or its mandate.

US ambassador John Bolton has hinted at a rapid reaction force going in first while a bigger more permanent force is assembled.

Bill Durch, a peacekeeping expert at the Henry Stimson Foundation in Washington and a consultant to the UN, said that while Hezbollah would have to stop shelling Israel and maybe disarm, Israel would also have to "promise to honour the border in the agreement" for an end to fighting.

"It would do so probably as long as that (international) force was doing its job," he cautioned, and Israeli Prime Minister Ehud Olmert emphasized in an interview with the Financial Times newspaper published Thursday that Israel would reserve the right to respond to any attack, even after a force is deployed.

Olmert said there should be at least 15,000 international troops. He told The Times newspaper in another interview that the force has to be "real soldiers", an "army with combat units that is prepared to implement the UN resolution."

Olmert also indicated Israel would maintain positions in southern Lebanon until the force arrives -- while Hezbollah insisted Thursday that it would not agree to a ceasefire while Israeli troops remain in Lebanon.

The question of who will lead the force is also controversial.

US President George W. Bush said this week that his country would "probably not" contribute troops. The US military is already stretched in Iraq and Afghanistan.

France has indicated it is ready to take part but refused to attend technical meetings on the force planned for this week because no political mandate has been agreed.

Diplomats and experts said, however, they would be stunned if France did not take a lead role.

Alexei Malachenko, an analyst at the Carnegie Centre in Moscow, said "no one is irreplaceable but it would be inconceivable to have a peacekeeping force in Lebanon without France. Lebanon sees France as the guarantor of its security."

The US role is controversial.

"The United States would be seen as the wrong actor in the region," Tim Williams, head of the European Security Programme at the London- based Royal United Services Institute (RUSI), told AFP. "There is an image concern."

But Durch, at the Henry Stimson Foundation, told the US National Public Radio (NPR) that a force without an American presence would also face problems.

"If the big dog is not playing all the other puppies are reluctant to join the fray," he said hinting at problems getting volunteers.

The United States has to be ready to say "we are not only willing to share the limelight on the political settlement and struggle, we are willing to share some of the risks on the ground," Durch said.

Turkey, Australia and India have been mentioned at the United Nations and other forums as potential contributors if a force is approved.

But because of the logistical problems of moving troops and equipment into place, Bob Ayers, from the foreign affairs centre Chatham House in London, said it could take six months to get the force active. (Copyright © 2006 Agence France Presse 08/03/06)