Britain and France have demanded that Muammar Gaddafi should stand down immediately and declared that the era of the Libyan leader is over.
On the eve of a conference on Libya in London, to be attended by more than 40 foreign ministers, Britain and France made clear they expected Gaddafi to face justice after launching attacks on Libya's civilian population.
Britain and France have clashed in the past week during the negotiations which led to an agreement to hand all aspects of the military campaign – the no-fly zone, protecting civilians threatened by Gaddafi's forces and enforcing an arms embargo – to Nato. But the two countries are keen to ensure pressure is maintained on Gaddafi by reminding the Libyan leader that UN security resolution 1970, passed last month, gave the international criminal court the authority to investigate the regime's attacks on civilians. The ICC is investigating whether war crimes have been committed.
Last night, Downing Street said that the prime minister David Cameron held a video conference about developments in the Middle East with US president Barack Obama, French president Nicolas Sarkozy and German chancellor Angela Merkel.
A Downing Street spokesman said: "The prime minister set out his priorities for the London conference on Libya: he hoped it would strengthen and broaden the coalition of countries committed to implementing the UN resolutions and protecting the people of Libya; it would discuss plans for the provision of urgent humanitarian assistance; and it would call for a political process which would allow the people of Libya to shape their own future.
"There was also a discussion of the reform process in Egypt and agreement on the importance of revitalising the Middle East peace process."
Cameron and Sarkozy had said earlier that there were no circumstances in which Gaddafi could remain in power. "In the words of the Arab League resolution, the current regime has completely lost its legitimacy. Gaddafi must therefore go immediately," they said.
The two leaders indicated that members of the Gaddafi regime who have not yet been listed in EU sanctions, could still escape prosecution if they abandon Gaddafi. Their statement added: "We call on all his followers to leave him before it is too late." Britain and France believe that the UN security council resolution, passed after violence erupted in Libya last month, should ensure that Gaddafi stands trial. The resolution says that the "Libyan authorities shall co-operate fully with and provide any necessary assistance to the [international criminal] court".
Britain hopes that the minds of Gaddafi and members of his regime will be concentrated if they are reminded of the "consequences of their actions". But Britain accepts that it may have to accept a deal, in which Gaddafi avoids justice by going into exile, as the price of peace.
Britain and France hope Tuesday's conference, to be attended by Hillary Clinton and representatives from five Arab states, the Arab League and the African Union, will map out a democratic future for Libya.
Britain is giving its unofficial blessing to the Interim National Transitional Council, based in Benghazi, by allowing senior figures to travel to London Tuesday to be briefed on the summit outside the venue at Lancaster House.
Cameron and Sarkozy showed their support for the transitional council. They said: "We call on all Libyans who believe that Gaddafi is leading Libya into a disaster to take the initiative now to organise a transition process. In our view, this could include the Interim National Transitional Council, the pioneering role of which we recognise, the civil society leaders as well as all those prepared to join the process of transition to democracy.
"We encourage them to begin a national political dialogue, leading to a representative process of transition, constitutional reform and preparation for free and fair elections."
France has recognised the transitional council as the legitimate representative of the Libyan people. Britain has not followed the French example because it recognises states and not governments.
Cameron and Sarkozy said that the military campaign has saved hundreds of thousands of people from a humanitarian disaster. But they offered reassurances to the Arab foreign ministers travelling to London for the summit that Britain and France have no intention of sending troops to occupy Libya. "We emphasise that we do not envisage any military occupation of Libya, which would be contrary to the terms of the [UN] resolution.
"We reaffirm our strong commitment to the sovereignty, independence, territorial integrity and national unity of Libya. Military action is not an objective as such. A lasting solution can only be a political one that belongs to the Libyan people."
Qatar became the first Arab country to recognise the rebels as the representative of the Libyan people, in a move that may presage similar moves from other Gulf states. Libyan state television called the move "blatant interference".
A US Treasury department official said rebels could sell Libyan crude without being subject to US sanctions if they conducted the transactions outside entities in Gaddafi's administration subject to sanctions. With its finances under pressure, the rebel leadership said it hopes to restart oil exports within a week.
Some energy traders said that, sanctions aside, they could not touch Libyan oil because of shipping and legal risks.
The conference, which is to be opened by Cameron, will be attended by foreign ministers from countries taking part in the military action and from other countries in the region. These include the United Arab Emirates which is providing 12 fast jets, six F-16s and six Mirages. Sheikh Hamad bin Jassim bin Jabr al-Thani, the Qatari prime minister whose jets have patrolled the no-fly zone, will also attend. Other key figures will be Ban Ki-moon, the UN secretary general, Dr Jean Ping, chairman of the African Union, and Dr Ekmeleddin Ihsanoglu, secretary general of the Organisation of the Islamic Conference (OIC).
The conference opens as an opinion poll shows seven out of 10 people fear military action in Libya could lead to a prolonged conflict. A ComRes poll for the Independent found 71% of people expressed concerns about a repetition of the Iraq conflict. Some 24% said they were not worried about a repeat. A large number of people, 47%, said they do not support British involvement in the military action, as against 43% who do.