Britain is working on plans for a military no-fly zone over Libya and is considering whether to arm the opposition forces in the east of the country.

David Cameron, the prime minister, said the UK is "taking the lead" on steps to isolate the "illegitimate" Gaddafi regime.

In a statement to the Commons, Cameron said north Africa and the wider Middle East was at the "epicentre of momentous events" sweeping through the region and that "hopes and aspirations which have been smothered for decades are stirring".

"For those of us who believe in democracy and open societies, [we] should be clear: this is a precious moment of opportunity," Cameron told MPs.

He revealed that he has asked the Ministry of Defence and the chief of the defence staff to work with the UK's military allies on plans for a military no-fly zone.

And he suggested that the British government would consider arming the opposition, following violence meted out against protesters.

The EU foreign policy chief, Catherine Ashton, told reporters after addressing the UN human rights council in Geneva that a no-fly zone was being discussed.

The Italian foreign minister, Franco Frattini, said European ministers had raised the issue of a no-fly zone with the US secretary of state, Hillary Clinton.

Clinton told the meeting that "nothing is off the table". However, US officials appear concerned that a vote on a no-fly zone could be harder to secure at the UN security council, where Russia and China may resist stronger action.

Asked if he had discussed a no-fly zone in his meeting with Clinton, the Russian foreign minister, Sergei Lavrov, told reporters: "Absolutely not. It was not mentioned by anyone."

The British foreign minister, William Hague, said that for a no-fly zone to work, it would need clear international support as well as the means to enforce it.

In London, Cameron confirmed British support for sanctions agreed by the European Union on Monday including an arms embargo, asset freeze and visa ban.

He vowed to look at "each and every way" of stepping up the pressure on Gaddafi's regime as he told MPs that the use of military assets was not "in any way ruled out".

"We must not tolerate this regime using military force against its own people," he said.

"For the future of Libya and its people, Colonel Gaddafi's regime must end and he must leave. To that end we are taking every step possible to isolate the Gaddafi regime, deprive it of money, shrink its power and ensure that anyone responsible for abuses in Libya will be held to account."

He told MPs during the debate that the government is trying to make contact with the Libyan opposition.

Pressed by the Conservative MP Bill Cash on whether the government would consider arming the opposition, the prime minister said it was something he would consider.

Outlining Britain's role in ousting Gaddafi, Cameron said the UK had drafted an "unusually strong" UN security council draft resolution, agreed over the weekend, which included a condemnation of Gaddafi's actions, a travel ban, an assets freeze, and refers the current Libyan leaders to the international criminal court.

Britain has already frozen the UK assets of Gaddafi, five of his family members, people acting for them or on their behalf and entities that are owned or controlled by them, following a special privy council session held on Sunday.

The Libyan leader's diplomatic immunity has been revoked so that neither he or his family can freely enter the UK, and visas have also been revoked for a number of Libyans linked to his regime.

Cameron said Britain has taken a "leading role" in the international rescue effort, which was being co-ordinated from Malta. During Sunday's rescue, only 21 of the 189 brought to safety were British nationals, he said.

But Cameron admitted there would be "lessons" to be learned about using chartered aircraft and defence assets in future.

He told MPs that events taking place in a number of Arab countries were an opportunity to "look again" at Britain's relationship with the region.

Cameron paid tribute to the armed forces, which had helped rescue some 600 British nationals stranded in Libya. He said fewer than 150 remain in Libya but many of those wanted to stay in the country.

He also revealed that one of the RAF C-130 Hercules involved in yesterday's mission to evacuate stranded oil workers had suffered minor damage from small-arms fire.