Libya no-fly zone having 'very real effect', says MoD
Maj Gen Lorimer said the operation had "blunted Col Gaddafi's assault on his own people".
The military operation over Libya is having a "very real effect", the Ministry of Defence says.
A spokesman said Col Muammar Gaddafi's assault on Benghazi had been "stopped in its tracks".
Coalition operations are into a fourth day, but fighting is still continuing on the ground in Libya.
Foreign Secretary William Hague said the operation would continue "as long as necessary" to achieve its aims and that the no-fly zone had saved lives.
Chancellor George Osborne says the cost of UK involvement should be modest compared with its role in Afghanistan.
He told the Commons the estimates were "in the order of the tens of millions not the hundreds of millions of pounds".
The Chief of the Defence Staff's spokesman, Maj Gen John Lorimer, highlighted the impact of the operation over Benghazi, the main stronghold of the rebels.
"Col Gaddafi vowed that his men would be going from house to house, room to room, to burn out the opposition," he said.
Armed reconnaissance"Libyan troops were reportedly committing atrocities in outlying areas of the city. The military intervention... has stopped that attack in its tracks."
At a briefing at the Ministry of Defence, Maj Gen Lorimer set out the latest details of the role British forces had played in the operation.
The RAF Typhoon is flying its first ever combat missions. Pilots say they went "very well".
He said RAF Typhoon jets flying from Gioia del Colle in southern Italy had flown their first mission into "hostile air space", supported by surveillance aircraft and tankers.
He said that, separately, Tornado GR4 ground attack planes had flown armed reconnaissance missions from their base at RAF Marham.
He added they had now gone to the forward base at Gioia del Colle.
Air Vice Marshal Phil Osborn confirmed that no British aircraft fired their weapons in last night's operations.
Other details of the operation also emerged from the briefing:
- RAF C-17 and C-130 transport aircraft have been "very busy" delivering personnel and equipment to bases around the Mediterranean
- Trafalgar class submarine, HMS Triumph, is on standby in case its Tomahawk missiles are required
- Frigates HMS Westminster and Cumberland are monitoring the Libyan coast
- The MoD says the Libyan navy has shown a "marked reluctance" to leave port since the operation began
The debate about who will take over control of the operation from the Americans in the next few days is continuing at a Nato meeting in Brussels.
Targeting Gaddafi
International law sounds like a solid structure with clearly defined parameters. It isn't. Does it tell us how far the coalition can go in targetting Colonel Gaddafi? Not readily.
That depends on the interpretation of the words "all necessary measures to protect civilians" in UN Resolution 1973.
Some would interpret these as permitting an attack on the head of the command and control organising armed attacks, others might not.
Much would depend on the role Col Gaddafi plays in any violent suppression.
So, what would happen if the coalition acted in breach of the resolution? Again, this is complex.
Any act amounting to a war crime or crime against humanity could be prosecuted at the International Criminal Court (ICC).
However, not all nations are signed up, the US being the most notable absentee.
So, for example, if British fighter pilots bombed a school - the kind of thing that regrettably happens in the fog of battle - they could in theory be prosecuted at the ICC, while US pilots could not.
BBC political correspondent Laura Kuenssberg said neither the UK nor France wanted sole charge, and there were moves towards a "hybrid operation" involving Nato.
Downing Street refused to set out its preferred option, but a spokesman said: "We need to make sure we have a structure in place that reflects the coalition parties."
Conflicting messages about whether targeting Col Gaddafi himself would be legal are continuing in Westminster.
The UN resolution authorises "all necessary measures", short of an occupying force, to protect Libyan citizens from the Gaddafi regime.
No 10 has said it believed it would be legal under certain circumstances to target the Libyan leader, but Britain's Chief of Defence Staff, Gen Sir David Richards, said it was "not allowed under the UN resolution".
'Assassination'William Hague stressed that the coalition should not be choosing the government of Libya.
"That is for the Libyan people themselves", he said. "But they have a far greater chance of making that choice now than they did on Saturday, when the opposition forces were on the verge of defeat."
Former Liberal Democrat leader Sir Menzies Campbell, who is a barrister, said the allies had no legal authority to seek regime change.
He told BBC Radio 4's The World At One: "If Col Gaddafi is, for example, in the lead tank in a column of tanks attacking a town filled with civilians, then that tank and Col Gaddafi would be a legitimate target.
"But he is not a legitimate target from the point of view of assassination."
Libya's government says more civilians were killed in the latest wave of air and missile strikes by coalition forces, but that can not be independently confirmed.
Fighting is continuing inside Libya between rebels and forces loyal to Col Gaddafi.
There are reports of shelling of the town of Misrata, and of fighting around the central town of Ajdabiya and in Zintan, south-west of Tripoli.
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