Nato should have complete command of military operations in Libya "in a couple of days", but a spokeswoman said the alliance saw no military solution to the crisis and hoped for a political settlement.
Nato agreed yesterday to take over all operations in Libya, putting the 28-country alliance in charge of airstrikes that have targeted Muammar Gadafy's military infrastructure, as well as a no-fly zone and an arms embargo.
France and Britain called today for Col Gadafy's supporters to drop him before it was "too late" and asked Libyans opposing him to join a political process to pave the way for his departure.
"Transition is under way. Nations are assigning assets to Nato authority as we speak," Nato chief spokeswoman Oana Lungescu told a news briefing today.
"That transition is not instantaneous. It's a phased transition that's expected to take place over a couple of days."
Nato officials said planning foresaw a 90-day operation, but they said the timetable would depend on the United Nations.
"It's planned for 90 days, but it doesn't mean it's limited to 90 days," one official said. "It's up to the United Nations to tell us how long they want us to do it for."
Ms Lungescu said Nato hoped the mission would be as short as possible.
"It's clear to everyone that there is no purely military solution to the crisis in Libya. What we hope and expect is that there will be a cessation of violence and that there will be a peaceful solution to this crisis and a transition to democracy, which is what the people of Libya want."
Ms Lungescu said a conference of 35 nations meeting in London tomorrow was expected to set out the "broad political lines" for a peaceful solution in Libya. One possible precedent would be the multinational force established for Bosnia in the 1990s.
All Nato member states are expected to participate in the Libya operation, directly or indirectly, she said.
Some members have put restrictions, known as caveats, on their operations, including the Netherlands, which has said it will only take part in air patrols, not attacks on ground targets, Nato staff officer Group Captain Geoffrey Booth said.
Canadian Lt-Gen Charles Bouchard, commander of the overall operation, said it had carried out its first missions in the no-fly operation, but transition to the broader role that would include ground strikes was still under way.
He said Nato's mission would be to "to help protect civilians and population centres from attack, or threat of attack" and declined to comment on recent airstrikes by Western forces, saying transition to full command was still underway.
"I will not comment on coalition operations," he said. "The exact time of the transition is still being coordinated. This is a very complex operation...the exact date is soon."
Lieut-Gen Bouchard also declined to detail Nato's rules of engagement when asked how it would respond if civilians were threatened by clashes between rebels and government forces.
"Every action that we take is always taken with care to ensure that minimal collateral damage takes place. Our job is to ensure the safety of people," he said.
Asked whether Nato, given the stated impartiality of its mission, would attack rebel forces if they were to threaten civilians, Ms Lungescu declined to comment.
"That's a hypothetical question. We are not going to go into details of the rules of engagement," she said. "We...leave it to operations commanders on the ground to direct operations day-to-day."
Reuters