The £43 million-per-month cost of the UK's military engagement in Libya has been defended by Defence Secretary Liam Fox as the "financial price to pay" for protecting civilians from brutal repression.
Taxpayers are expected to face a total bill of around £260 million if the Nato-led mission lasts six months, according to figures released by the Ministry of Defence (MoD).
The projected total consists of £120 million mounting the multinational United Nations-endorsed operation and £140 million-worth of missiles and other munitions.
It is significantly higher than the eight-figure sum suggested by Chancellor George Osborne at the time of the opening salvoes in March - when military strategists expected a swifter result.
Dr Fox said the cost, being met from Treasury reserves, was inflated by the need to use precision weaponry in air strikes against Muammar Gaddafi's forces in order to minimise innocent casualties.
"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."
Details of the cost were released as Gaddafi seized on recent civilian deaths to brand the military alliance "murderers".
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.
Military chiefs have publicly expressed doubts about the UK's capacity to continue the Libya campaign at the same intensity - sparking a dressing down by Mr Cameron.
Former Chief of the Defence Staff, Air Chief Marshal Lord Stirrup, said the campaign in Libya could be afforded. "It is a large sum of money when you put it like that," he said. "But in the context of the overall GDP of the UK, of the overall budget, and indeed of the deficit which we are trying to eliminate, this really is very small beer."