Libya: British missiles fired at military sites
British jets and a submarine have fired missiles at Libyan military sites as part of a UN-backed international operation to enforce a no-fly zone.
Prime Minister David Cameron called the action "legal, necessary and right".
RAF Tornados flew 3,000 miles from RAF Marham, in Norfolk, and back to carry out their bombing mission.
France, US, Canada and Italy are also involved in the operation to protect civilians from attacks by Libyan leader Col Muammar Gaddafi's forces.
A British Trafalgar Class submarine and US submarines fired a total of more than 110 Tomahawk missiles at Libyan targets.
French planes had destroyed Libyan vehicles earlier on Saturday. US officials said it was a "carefully co-ordinated" joint operation known as Odyssey Dawn.
Defence Secretary Liam Fox said the Tornados' flights out of RAF Marham had been "the longest range bombing mission conducted by the RAF since the Falklands conflict".
Chancellor George Osborne, who attended a meeting of the emergency Cobra committee prior to Saturday's operation, said the terms of the UN mandate authorising the action were "very clear".
"We have to make sure the will of the United Nations is felt," he told the BBC.
The UK was part of an "incredibly broad coalition", he said, and there was evidence the French and UK air strikes had "already had some effect" in reducing attacks on civilians in Benghazi.
"We are not considering ground forces at the moment", he added.
The operation was supported by VC10 and Tristar air-to-air refuelling aircraft as well as E3D Sentry and Sentinel surveillance aircraft, the Ministry of Defence (MoD) said.
HMS Westminster is off the coast of Libya and HMS Cumberland is in the region ready to support operations, an MoD statement added.
Libyan state TV reported that what it called the "crusader enemy" had bombed civilian areas of Tripoli, as well as fuel storage tanks supplying the western city of Misrata.
A Libyan government spokesman described the coalition attacks as "aggression without excuse" and claimed Col Gaddafi had accepted the UN resolution and declared a ceasefire.
He claimed many civilians had been hurt and said ambulance crews had been "doing their best to save as many lives as possible".
A US military spokesman said they would have to wait for daylight before they could assess the success of the missile strikes.
After hosting a meeting of the government's emergency management committee Cobra in Downing Street, Mr Cameron said: "British forces are in action over Libya. They are part of an international coalition to enforce the will of the United Nations.
"We have all seen the appalling brutality meted out by Col Gaddafi against his own people."
It was a "just cause" and in "Britain's best interests", he added.
The Chief of Defence Staff's strategic communications officer Maj Gen John Lorimer said: "This is the first stage. UK and partner forces remain engaged in ongoing operations as we seek to ensure that Col Gaddafi and his forces understand that the international community will not stand by and watch them kill civilians."
Labour shadow defence secretary Jim Murphy said: "We are trying to achieve something relatively precise, which is to stop Gaddafi, his military, his heavy artillery, his tanks, his aeroplanes, from being able to make attacks upon civilian centres.
"And I think that can be done in the way in which the UN's outlined. It won't happen immediately, but I think it can be done."
The former British ambassador to Libya, Oliver Miles, told the BBC it was clear the long-term aim of the military action was to overthrow Col Gaddafi.
Conservative MP Col Bob Stewart, who was a UN commander in Bosnia, predicted that Col Gaddafi's forces would desert their leader.
"The onus is back on people in Libya to make their decision. I really am totally with the idea that all we've done is to stop the killing.
"I've watched what happened in Sarajevo in 1992 and 1993 and could see a repeat of that in Benghazi with brutes shelling civilians," he said.
A British journalist was being held by Libyan authorities in the capital Tripoli, Arab television station Al Jazeera revealed on Saturday night.
Cameraman Kamel Atalua was detained with a fellow cameraman and two correspondents, after the team had been reporting from Libya for several days.
The military action follows the passing of a UN resolution imposing a ban on all flights in Libyan airspace, excluding aid flights, and authorises member states to "take all necessary measures" to "protect civilians and civilian populated areas under threat of attack".