US, European and Arab leaders on Saturday held a Libya crisis summit with the threat of military strikes against Muammar Gaddafi's forces growing ever more intense.
A senior French envoy predicted strikes against the Libyan leader could start within hours of the summit. The United States has also declared that Gaddafi is in breach of a UN Security Council resolution which ordered an immediate ceasefire.
An ultimatum sent by France, Britain, the United States and Arab countries to Gaddafi late Friday warned him to "immediately" cease all attacks on his people or face the consequences.
France's ambassador to the UN, Gerard Araud, told the BBC he expects military action in Libya "in the coming hours" after the Paris summit.
President Nicolas Sarkozy will host the crisis summit to be attended by prime ministers David Cameron of Britain, Silvio Berlusconi of Italy, Jose Luis Rodriguez Zapatero of Spain, German Chancellor Angela Merkel, US Secretary of State Hillary Clinton.
Government leaders from Belgium, Denmark, Greece, Netherlands, Norway, Portugal and Poland are also at the summit, diplomats said. UN Secretary General Ban Ki-moon and leaders from the European Union, Arab League and African Union are also attending.
Sarkozy, Cameron and Clinton discussed sharing out the military roles ahead of the summit, sources said. France and Britain would focus on air strikes, while other NATO countries would police the no-fly zone, the sources said.
They were also to choose a top officer to lead the campaign.
So far Belgium, Britain, Canada, France, Italy, Norway, Spain, Sweden, Qatar and the United States have said they will help to implement a no-fly zone that was authorised by UN Security Council resolution 1973 passed on Thursday.
Western nations have called for strong Arab support for the military operation after Arab League foreign ministers called for the no-fly zone over Libya last week. In response, Jordan, Morocco, Qatar, United Arab Emirates and Arab League Secretary General Amr Mussa will be at the summit.
EU foreign policy chief Catherine Ashton and EU president Herman Van Rompuy will also be in Paris.
The statement released by France and other allies said that "a ceasefire must be put in place immediately, that is, that all attacks against civilians must come to an end".
It demanded that Gaddafi forces halt their advance on the rebel capital of Benghazi and withdraw from the cities of Ajdabiya, Misrata and Zawiyah. "That is not negotiable," it warned.
If Gaddafi did not comply with the Security Council resolution, he would face "consequences" from the international community and "the resolution will be imposed by military means".
"Left unchecked, we have every reason to believe that Gaddafi would commit atrocities against his people," US President Barack Obama said, reinforcing the international message. "Many thousands could die. A humanitarian crisis would ensue."
Gaddafi declared a ceasefire on Friday but Libyan rebels said fighting goes on.
Details of the role of each country in the threatened action remain vague.
The British prime minister said his country would deploy Tornado and Typhoon warplanes as well as air-to-air refuelling and surveillance aircraft to airbases "from where they can take the necessary action".
Britain has an airbase on the eastern Mediterranean island of Cyprus.
France has not yet announced what planes or facilities it is preparing.
Canada has announced the deployment of six CF-18 fighter jets to help enforce a no-fly zone.
Obama has left unclear the exact role that the United States would play in military action, beyond enabling European and Arab partners to "effectively" mount a no-fly zone.
He made clear, however, that there would be no US ground troops deployed to Libya.