By John Irish and Mohammed Abbas
PARIS/MISRATA, Libya (Reuters) - Western forces plan to use attack helicopters in Libya to help break a military stalemate with forces loyal to Muammar Gaddafi, a French diplomatic source said on Monday.
Continued shelling of the rebel-held western outpost of Misrata illustrated the scale of the problem facing rebel forces and NATO. Rebels said Gaddafi forces were trying to advance into the long-besieged city under cover of rocket and mortar shells.
A rebel spokesman said forces loyal to Gaddafi also shelled the rebel-held town of Zintan and massed troops close to another town in the mountainous region bordering Tunisia, intensifying operations on the war's western front.
The French daily Le Figaro reported that 12 helicopters, which could launch more accurate attacks on pro-Gaddafi forces and targets than fixed wing aircraft, were shipped out to Libya on the French warship Tonnerre on May 17.
"It is not just French helicopters ... it's coordinated action by the coalition," the diplomatic source said, in response to the newspaper report. "It is at NATO level."
The source said the move could not be considered as part of a strategy to use ground troops in the conflict, now in its fourth month.
A U.N. Security Council resolution allows NATO to strike Gaddafi forces in defence of civilians, but it explicitly excludes any military occupation. Critics such as Russia accuse NATO of overstepping their mandate in prosecuting a systematic campaign to force the end of Gaddafi's 41-year rule.
NATO declined to comment and referred questions to the French Defence Ministry. French military spokesman Thierry Burkhard declined to confirm the report.
British Foreign Secretary William Hague said he agreed it was necessary to intensify pressure on Gaddafi's forces, but declined to say if Britain planned join a helicopter deployment.
According to Le Figaro's source, French special forces, who have been operating in Libya to help identify targets for NATO planes since the start of air strikes, could now be reinforced and deployed to guide helicopter attacks.
MORE RISKY
The use of helicopters, while it could allow NATO forces to launch more accurate attacks, would pose additional risks for NATO. Helicopters would fly lower and be more vulnerable than aircraft flying well above depleted air defences. The downing of helicopters could draw ground forces into rescue efforts.
"Twelve helicopters is not a lot," Ken Freeman, associate fellow of the Royal United Services Institute for Defence and Security Studies (RUSI). "They tend to be quite vulnerable, so they are probably going to be used very carefully .. You could probably say it is a sign that people are running out of ideas."
Intensifying the diplomatic activity ahead of a G8 meeting of world powers in France this week, the most senior U.S. diplomat to visit during the uprising arrived in the eastern city of Benghazi for talks with leaders of the rebellion.
Jeffrey Feltman, assistant secretary of state for the Near East, met members of the National Transitional Council formed to administer the eastern regions under rebel control, on the heels of EU foreign policy chief Catherine Ashton's visit on Sunday.
"We are here for the long term and what we can offer is support to Libyan institutions and the economy. We will be here to support you all the way," Ashton said.
Gaddafi describes his opponents as religious extremists, criminals and foreign-backed mercenaries. He says he has no intention of stepping down after the manner of Tunisian and Egyptian autocratic leaders overthrown in an "Arab Spring" of democratic protest that swept the Middle East.
OIL CHIEF DEFECTION?
Russian Foreign Minister Sergei Lavrov said he would meet a Libyan "opposition" delegation on Monday to try to promote a cease-fire and negotiations.
"It is important at this stage to agree a makeup of participants in future talks -- which I hope will be soon but are inevitable in any case -- that would represent the interests of all the political forces, all the tribes in Libya," he said.
The rebels have refused proposals for a cease-fire and talks from the Gaddafi administration, arguing that he has broken previous unilateral ceasefires. They insist Gaddafi, his allies and his family must renounce power as part of any settlement.
As rebel hopes of a military victory have faded, Gaddafi opponents in Libya and Western governments have sought the collapse of the Libya administration from within, encouraging defections of senior officials.
Tunisia said on Monday Libya's top oil official was in Tunisia and believed to be no longer working for Gaddafi. There has been doubt about Shokri Ghanem's fate since rebels said last week he had defected -- a charge Tripoli has denied, saying he was merely on an official trip to Tunisia, Europe and Egypt.
"I believe and I suspect Mr Ghanem just left Libya and that he is not any more working with the Gaddafi regime. Probably that's why he came to Tunisia," Tunisian Foreign Minister Mouldi Kefi said on a visit to Tokyo.
Ghanem was staying in a hotel on a small southern Tunisian island, he told a news conference.
The most prominent Libyan defector so far is Moussa Koussa, the foreign minister who fled to Britain in March. A Tunisian security source also said last week that Gaddafi's wife Safia and daughter Aisha were on the Tunisian island of Djerba.
Separately, Tunisia's official news agency TAP said a number of Libyans, including Foreign Minister Abdelati Obeidi and Libya's ambassador to Liberia, had crossed into Tunisia at Ras Jadir. It was not immediately clear why they were travelling.
(Additional reporting by Joseph Logan in Tripoli, Sherine El Madany in Benghazi and Joseph Nasr in Berlin; David Brunnstrom in Brussels and Avril Ormsby in London; Writing by Ralph Boulton and Jan Harvey; Editing by Alison Williams)
