France and other members of the Nato-led coalition planned to deploy attack helicopters in Libya, a French diplomatic source said yesterday, a move aimed at ramping up pressure against Muammar Gaddafi's forces.

Twelve helicopters were shipped to Libya on the French helicopter carrier Tonnerre on 17 May, Le Figaro reported earlier, to help break a military stalemate three months into an uprising against Colonel Gaddafi's four-decade rule.

"It is not just French helicopters ... It's co-ordinated action by the coalition," the source said. "It is at Nato level."

Nato bombing has damaged Colonel Gaddafi's armour, but not enough to break the deadlock. While helicopters could make it easier to hit urban or embedded targets, they would also be more vulnerable to ground fire.

"Using helicopters from the Tonnerre is a way of getting closer to the ground," Le Figaro said, citing a source close to the matter.

French planes were the first to bomb Libyan forces in March after the United Nations voted to allow intervention to protect civilians.

Many Nato members refuse to go beyond enforcing a UN-mandated no-fly zone to attack Colonel Gaddafi's forces, despite the urging of France, Britain and the United States, which all want to see the dictator removed from power.