UK military operations in Libya are costing taxpayers more than £40 million a month, Defence Secretary Liam Fox said today.
In a written statement to MPs, Dr Fox said the projected cost of the six-month, Nato-led campaign was "in the region of £120 million".
Another £140 million would have to be spent replacing missiles and other munitions if the mission continued at the same rate, he told MPs.
"The Treasury has agreed to meet these costs from the reserve," he added.
Details of the costs of the Libya operation were issued by the Ministry of Defence after days of pressure from Labour for a full assessment.
Chancellor George Osborne suggested when the United Nations-authorised campaign began in March that it would cost tens, not hundreds, of millions.
But his deputy, Chief Secretary Danny Alexander, conceded at the weekend that it was running into the "hundreds of millions".
Earlier this month, Nato extended the duration of the multi-nation campaign against forces loyal to Muammar Gaddafi for another 90 days beyond the original cut-off of June 27.
Some suggest the cost could rise to £1 billion if raids drag on into the autumn. The spending is being met from Government reserves rather than normal budgets.
Defending the spending, Dr Fox said the high costs were partly down to the use of expensive precision weaponry "so that we minimise civilian casualties in Libya".
"And if we are going to fight operations in the future based on minimising civilian casualties there is clearly a financial price to pay," he said.
"But I think that that shows that we are on the moral high ground and that we place a higher value on human life than the Gaddafi regime does."
Prime Minister David Cameron has insisted that British forces can maintain the current level of operations in Libya despite concerns raised by senior military figures.
Gaddafi broke his recent radio silence last night to accuse the military coalition of murdering family members of a close aide.
Nato said it regretted any civilian casualties but insisted that the air strike was carried out on a residence used as a command and control centre.
A son of the dictator was among those killed in an earlier raid on his compound.
At the weekend, the Alliance blamed a "weapons system failure" for a bomb or missile landing in a residential area of the capital Tripoli and expressed regret at the death toll.
RAF fighter planes, using a southern Italian base, flew their first sorties on March 19 - two days after the United Nations Security Council authorised "all necessary measures" to protect Libyan civilians from Gaddafi's brutal repression of a popular uprising.
On May 27, Army Air Corps Apache combat helicopters joined the fray as the military pressure on Gaddafi to quit was stepped up.Reuse content