NATO leaders were quick to dispel rumours Thursday that the military alliance is moving toward deploying ground forces to the conflict in Libya.

British Prime Minister David Cameron told BBC Scotland radio that NATO and its allies must "turn up the pressure," but wouldn't deploy troops.

Italy, France and Britain are sending military experts to act as advisers to Libya's opposition forces as they struggle to loosen Moammar Gadhafi's grip on power. But leaders of all three countries insisted NATO would not escalate its presence.

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A rebel fighter prepares a belt of ammunition for his heavy machine-gun on the front line outside Ajdabiyah. NATO supports the rebels, but has not deployed ground troops. ((Amr Abdallah Dalsh/Reuters))

Cameron said the UN Security Council resolutions meant allies were "not allowed, rightly, to have an invading army."

"That's not what we want, that's not what the Libyans want, that's not what the world wants," Cameron said.

He said allies should consider additional sanctions, including on oil revenue that the U.K. says Gadhafi continues to receive.

Hours earlier, President Nicolas Sarkozy said France would step up its share of the NATO-led airstrikes aimed at knocking out Gadhafi's military apparatus to protect civilians.

"We will help you," Sarkozy promised the Libyan opposition council's visiting president, Mustafa Abdel-Jalil, who said he had asked France "to intensify the support accorded to the Libyan revolution."

"We will intensify the strikes," Sarkozy responded, according to a presidential aide who was not authorized to be publicly named according to policy.

French Foreign Ministry spokeswoman Christine Fages said in an online briefing Wednesday that France had also agreed to place "a small number of liaison officers alongside our special envoy in [the rebel stronghold] of Benghazi."

Italy, too, announced plans to send help — 10 military instructors — although Defence Minister Ignazio La Russa, ruled out sending ground troops. Britain said Tuesday it was sending up to 20 military advisers to help Libya's rebel forces.

Cameron spoke separately Wednesday with U.S., Italian and Qatari leaders.

A Downing Street spokesperson, speaking on customary condition of anonymity, said Cameron "emphasized the urgent importance of placing continued military and diplomatic pressure on the Gadhafi regime in order to protect the many thousands of civilians who remain under attack."

The spokesperson added that there "was strong agreement on the need to enforce" the UN Security Council resolution opening the way to a military mission to protect civilians.

'We remain resolute in seeking a rapid political transition in Libya.'—EU foreign policy chief Catherine Ashton

EU foreign policy chief Catherine Ashton went a step further, saying out loud what other nations often prefer to whisper.

"For the European Union, we remain resolute in seeking a rapid political transition in Libya," Ashton told reporters in Abu Dhabi, where she was attending meetings. "We believe the Gadhafi regime must cede power and allow the Libyan people to determine their own future."

In Washington, the Obama administration approved the use of armed Predator drones in Libya, authorizing U.S. airstrikes against ground forces.

U.S. officials also said Gadhafi's forces might be targeting civilians with cluster bombs.

"Col. Gadhafi's troops continue their vicious attacks, including the siege of Misrata," U.S. Secretary of State Hillary Clinton told reporters in Washington on Thursday. "There are even reports that Gadhafi forces may have used cluster bombs against their own people."

The White House announced on Wednesday it plans to give the Libyan opposition $25 million in non-lethal assistance — the first direct U.S. aid to the rebels — after weeks of assessing their capabilities and intentions.

Washington ensured that the surplus American goods couldn’t be converted into offensive military assets, officials said.

Border crossing seized

Meanwhile, on the ground Thursday, rebels claim to have taken control of a crossing on the Tunisian border near Dhuheiba. Rebel leaders claim to have seized the outpost about 240 kilometres from Tripoli, but the claim has yet to be verified as Gadhafi has sharply restricted access to Western journalists.

If the report is true and the rebels can hold the crossing, not only does it give them a second foothold in western Libya, but would also open important supply routes for anti-Gadhafi forces.

In the rebel stronghold of Benghazi in eastern Libya, relief workers and medical teams awaited the arrival Thursday of a passenger ferry carrying about 1,000 people — mostly Libyan civilians and workers from Asia and Africa — out of the besieged city of Misrata, the main rebel holdout in Gadhafi's territory.

Also aboard the vessel were the bodies of an Oscar-nominated documentary maker from Britain and an American photographer, who were killed covering clashes Wednesday. A day earlier, the ferry arrived in Misrata, delivering food and medical supplies.

With files from The Associated Press