By Tsvetelia Tsolova
VARNA, Bulgaria (Reuters) - Muammar Gaddafi's rule is in its final stages, top NATO officials said on Monday, and the alliance might consider sending a small force into Libya once he leaves power.
NATO powers are ratcheting up their intervention in Libya to try to break a deadlock that has seen Gaddafi hold on to power despite weeks of air strikes and a rebel uprising.
"Gaddafi's reign of terror is coming to an end. He is increasingly isolated at home and abroad. Even those closest to him are departing, defecting or deserting," Secretary-General Anders Fogh Rasmussen told a NATO forum in Varna.
NATO warplanes have intensified their air strikes on Tripoli and have repeatedly hit Gaddafi's Bab al-Aziziyah compound in the center of the city.
"We will keep up the pressure until all attacks and threats of attacks against civilians have stopped, until the regime has withdrawn its forces and mercenaries to bases and barracks," said Rasmussen.
Rebels now control the east of the country, around their main stronghold in Benghazi, and pockets in the West.
But the conflict has reached stalemate on ground, with the rebels unable to advance toward Tripoli and NATO powers -- wary of getting sucked into new conflicts after their experience in Iraq and Afghanistan -- refusing to put troops on ground.
U.S. Admiral Samuel Locklear, commander of the Joint Operations Command at Naples conducting the Libya campaign, declined to comment whether NATO would expand its operation with forces on ground.
But he suggested that a small force may be needed once Gaddafi's regime collapses to help the transition to democracy after his 41 years in power.
He told the Varna forum: "I would anticipate that there might be a need at some point to unfold a small force ... a small number of people there to help them in some way."
"It could be the United Nations, it could the European Union, I guess for a short period of time it could be NATO," he added without elaborating.
Locklear said NATO was not carrying out plans on deploying such a force, but was discussing it because the alliance may be forced to act quickly to avoid a possible vacuum of power.
"I think, given where we come in this operation that it would be, may be in the best interest as they try to put a government together to provide them some stability and some support while they do that," Locklear said.
Britain said on Sunday it was adding "bunker-busting" bombs to the weapons its warplanes are using over Libya to send the Libyan leader the message that it was time for him to step down.
(Writing by Radu Marinas; editing by Philippa Fletcher)