British military chiefs are developing plans for a no-fly zone over Libya, David Cameron has told the Commons.
The prime minister said he was prepared to use force as part of a bid to increase pressure on Muammar Gaddafi's regime.
"We do not in any way rule out the use of military assets," he said.
"We must not tolerate this regime using military force against its own people."
The chief of the defence staff and the Ministry of Defence have been asked to prepare for the implementation of a no-fly zone in conjunction with Britain's allies, in a bid to prevent Col Gaddafi using military jets against his own people.
"We welcome what he says about a possible no-fly zone," Labour leader Ed Miliband said.
Mr Cameron laid out plans to isolate Col Gaddafi's regime further, following action taken by the UK government at the weekend.
"We will look at each and every way of stepping up pressure on this regime," he pledged.
These included "further isolation of the regime by expelling it from international organisations and further use of asset freezes and travel bans to give the clearest possible message to those of the fringes of the regime, that now is the time to desert it".
Mr Miliband called on Mr Cameron to apologise again for the government's initial failure to get British citizens out of Libya quickly.
He asked the prime minister: "The whole country has thankfully now seen the scale of the response that can be mobilised to help our citizens, but can he promise that British citizens overseas in the future won't be let down by the chaos and incompetence seen last week?"
Mr Cameron replied by suggesting that Mr Miliband should consider apologising for the last government's "appalling dodgy dealing" with the Libyan government.
Hague wants Libyan 'day of reckoning'
In Geneva, foreign secretary William Hague called on the UN human rights council to suspend Libya from the organisation.
Speaking at the council's Geneva headquarters, the foreign secretary warned all those committing human rights violations in Libya to "stay your hand".
"There will be a day of reckoning and the reach of international justice can be long," Mr Hague said.
"We must now maintain the momentum we have attained to ensure that there can be no impunity for crimes committed in Libya and to help bring about an immediate end to the violence."
Mr Hague's rhetoric came after a weekend in which the British government hardened its attitude against Libya, calling on Col Gaddafi to abandon power immediately even as RAF transport planes evacuated British oil workers from the Libyan desert.
Much of Libya has already fallen into the hands of anti-Gaddafi forces. Reports emerged this lunchtime of the first protests against his regime on the streets of his capital, Tripoli.
"The unanimous response to the crisis in Libya, here in the human rights council and at the UN security council, was remarkable," Mr Hague added.
"The international community came together in a way which it has not done before, setting aside differences in the face of a challenge to the very notion of what we commonly and instinctively regard as the basic rights of humankind.
"Together we have signalled that crimes will not be condoned, will not go unpunished and will not be forgotten."
His remarks were quickly followed by news that the European Union is to introduce its own set of sanctions against Libya, after the US unilaterally imposed sanctions against the Gaddafi regime.