RAF warplanes today destroyed ammunition dumps being used by Muammar Gaddafi's regime to attack the opposition-held city of Misrata, the Ministry of Defence announced.
Tornado GR4 jets flew from RAF Marham in Norfolk on strike missions against bunkers in the Sabha area of the desert in southern Libya in the early hours of the morning.
The planes used Storm Shadow missiles to destroy the bunkers, which contained ammunition intended for use in attacks on Misrata and other northern cities, said the MoD.
The mission followed armed reconnaissance sorties over Libya during the weekend during which RAF Tornados hit a total of 22 tanks, armoured vehicles and artillery pieces in the vicinity of Misrata and Ajdabiya, said the Chief of Defence Staff's Major General John Lorimer.
Maj Gen Lorimer added: "Following the retreat of Colonel Gaddafi's forces from most of the coastal towns east of Sirte, RAF Tornados have joined other coalition aircraft patrolling over Misrata where, despite significant losses as a result of air strikes, the regime continues to mount attacks on the town.
"During the early hours of this morning, Tornado GR4 aircraft conducted strike missions against Libyan ammunition bunkers in the Sabha area in the southern Libya desert. Tornado GR4 aircraft flew from RAF Marham and were refuelled en route by Tristar tanker aircraft from RAF Brize Norton.
"Storm Shadow missiles were launched against ammunition bunkers used to re-supply Libyan government troops attacking civilians in the north of the country, including Misrata.
"Initial reports suggest that the bunkers have been destroyed and that the Libyan government has been denied ammunition it uses to threaten civilians in the north of the country."
Rebel forces were today celebrating the seizure of the key oil towns of Brega and Ras Lanuf, potentially giving them control of much of Libya's export capacity.
However, there was doubt over claims that the opposition had also seized the city of Sirte, Col Gaddafi's birthplace and a stronghold of the regime.
The rebels' sweep westwards towards the capital, Tripoli, has been assisted by coalition air strikes targeting regime tanks and armoured vehicles, but has sparked allegations from Gaddafi loyalists that the international forces are effectively acting as air cover for revolutionary forces.
Nato Secretary-General Anders Fogh Rasmussen denied today that the alliance was co-ordinating its military action with the Libyan opposition, and warned that commanders in the field were authorised to take action to protect civilians from rebels as well as from Col Gaddafi's forces.
Prime Minister David Cameron will update MPs on the latest situation in Libya in an oral statement to the House of Commons later today.
Mr Cameron chaired a meeting of the National Security Council's Libya sub-committee this morning to take stock of the situation on the ground and prepare for tomorrow's London conference.
The conference will bring together delegations from more than 40 countries, as well as United Nations Secretary-General Ban Ki-moon, to discuss the implementation of Security Council resolutions on Libya; preparations for any humanitarian emergency in the country; post-conflict stabilisation; and the political way forward to allow the Libyan people to move to a more open and democratic government.
The PM's official spokesman was unable to confirm whether any representatives of the Libyan opposition would be present, but said it was not the purpose of the conference to choose leaders for a post-Gaddafi government in Tripoli.
"We have always been very clear that what follows should be a matter for the Libyan people, not for us or for any other country, to decide," he told reporters at a Westminster briefing.
"It is not for us to identify the future government of Libya."
Today's attacks came after Nato agreed to take command of all international military operations over Libya, including air strikes on Col Gaddafi's ground forces.
The agreement by alliance ambassadors, meeting last night in Brussels, paves the way for the United States to relinquish its temporary leadership of the operation, ending days of diplomatic wrangling.
Nato had previously agreed to take charge of enforcing the United Nations no-fly zone and arms embargo.
However some member states - notably Turkey and Germany - had baulked at taking on the air strikes as well because of the risk of civilian casualties.
Mr Rasmussen said it was a "very significant step" by the alliance.
"Our goal is to protect civilians and civilian-populated areas under threat of attack from the Gaddafi regime. Nato will implement all aspects of the UN resolution. Nothing more, nothing less," he said.
Asked on the BBC Radio 4 Today programme whether Nato would intervene militarily to prevent attacks on civilians by rebels, he replied: "It is a hypothetical question, because until now it is the Gaddafi forces that have attacked civilians, but our obligation is to ensure full implementation of the UN Security Council resolution and protect civilians against all attacks.
"I don't think the rebels will attack civilians. If so, we have to protect civilians against attack.
"Those who attack civilians will also be our targets, but I have to stress that until now it is the Gaddafi regime that has attacked its own people."
Mr Rasmussen declined to reveal the exact terms of the rules of engagement in Libya or to estimate how long the current operations may take.
"It is premature to lay out any timetable, but I hope to see a peaceful resolution to the problems in Libya as soon as possible," he said.
"Clearly, there is no military solution solely. It is for the Libyan people to decide what should be the future of Libya."
Asked whether Libya could become "another Iraq or Afghanistan", causing instability across the region, he replied: "We should definitely avoid that. This is the reason why I would strongly urge all parties involved to find a peaceful and political solution as soon as possible."
Russia warned today that attacks on Col Gaddafi's forces on the ground amounted to intervention in a civil war and were not backed by the UN resolution authorising a no-fly zone.
And Turkish Prime Minister Tayyip Erdogan told The Guardian that his country was prepared to act as mediator to broker an early ceasefire in Libya, warning that a lengthy conflict risked turning the north African state into a second Iraq.
Mr Cameron's spokesman said: "We want to see a ceasefire, but we want to see a genuine ceasefire."
Nato's assumption of command and control responsibilities would "strengthen the position politically", said the spokesman.
Asked whether the coalition would protect civilians against attack by rebel forces as well as those of the Gaddafi regime, Mr Cameron's spokesman said: "The Prime Minister has made clear that everything we do needs to be consistent with the UN Security Council resolution.
"The Security Council resolution talks about protecting civilians and that means all civilians. The context is that there were peaceful protests going on in Libya and they were brutally put down by the Gaddafi regime."
In a joint statement issued ahead of tomorrow's conference, Mr Cameron and French President Nicolas Sarkozy said that the event would allow the international community to "come together to support a new beginning for Libya.
"A new beginning in which the people of Libya are free from violence and oppression, free to choose their own future".
The coalition's action to break the siege of Benghazi and drive back Gaddafi's forces had rescued hundreds of thousands of people "from the brink of humanitarian disaster", they said.
Mr Cameron and Mr Sarkozy added: "Our countries are resolved to continue to enforce UN Security Council Resolution 1973 to protect the people of Libya. More countries from Europe and the Arab world are joining us.
"It is only when the civilian population are safe and secure from the threat of attack and the objectives of UNSCR 1973 are met that military operations will come to an end.
"We emphasise that we do not envisage any military occupation of Libya, which would be contrary to the terms of the Resolution. We reaffirm our strong commitment to the sovereignty, independence, territorial integrity and national unity of Libya."
The two leaders stressed that military action was not an objective in itself and that a lasting solution can only be reached through a political process involving the Libyan people.
"That is why the political process that will begin tomorrow in London is so important," they said. "The London Conference will bring the international community together to support Libya's transition from violent dictatorship and to help create the conditions where the people of Libya can choose their own future."
The current regime has "completely lost its legitimacy" and Gaddafi must "go immediately", said Cameron and Sarkozy.
"We call on all his followers to leave him before it is too late. 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."
Tomorrow's conference will also discuss how to avoid a humanitarian crisis in Libya by delivering urgent relief now and supporting the needs of the Libyan people in the longer term, said the two leaders.
"In the last few weeks, the Libyan people have demonstrated their courage and their determination. Like all other peoples, they have the right freely to choose their leaders," said Mr Cameron and Mr Sarkozy.
"We must unite to help them make a new beginning."