UN backs action against Gaddafi
In New York, the 15-member body voted 10-0 in favour, with five abstentions.
Libyan leader Col Muammar Gaddafi's forces have recently retaken several towns seized by rebels in an uprising.
Rebel forces reacted with joy in their Benghazi stronghold but a government spokesman condemned UN "aggression".
Loyalist forces are bearing down on Benghazi, home to a million people.
'Threatens unity'
Following the vote US President Barack Obama called the French and British leaders to discuss the next move. They said Libya must comply immediately with the resolution.
It is not thought that the US would be involved in the first strikes, but the British and French are likely to get logistical backup from Arab allies. There were reports military action could come soon.
The UK, France and Lebanon proposed Security Council Resolution 1973, with US support.
Russia and China - which often oppose the use of force against a sovereign country as they believe it sets a dangerous precedent - abstained rather than using their power of veto as permanent members.
French Foreign Minister Alain Juppe, introducing the resolution, said: "In Libya, for a number of weeks the people's will has been shot down... by Colonel Gaddafi who is attacking his own people.
"We cannot let these warmongers do this, we cannot abandon civilians."
He added: "We should not arrive too late."
The US ambassador to the UN, Susan Rice, said: "This resolution should send a strong message to Colonel Gaddafi and his regime that the violence must stop, the killing must stop and the people of Libya must be protected and have the opportunity to express themselves freely."
British ambassador to the UN, Sir Mark Lyall Grant, said: "The international community has come together in deploring the actions of the Gaddafi regime and demanding that the regime end this violence against the Libyan people." He said the UK was "ready to shoulder our responsibility".
But Germany, which abstained, will not be contributing to the military effort. Foreign Minister Guido Westerwelle said his government sees "considerable dangers and risks" in military action against Col Gaddafi.
There was a joyful response to the vote among rebels in Benghazi. Locals cheered, fired guns in the air and let off fireworks to celebrate the imminent no-fly zone; Kazinform cites BBC News.
See www.bbc.co.uk for full version