Defense Secretary Liam Fox said Thursday, June 23, that NATO's air-led campaign in Libya is costing British taxpayers more than 40 million pounds ($64 million) a month.

Fox said if the mission continues at the same rate, the military will need to spend another 140 million pounds replacing missiles and other munitions, The Associated Press reported.

The projected cost of a six-month, NATO-led operation was "in the region" of 120 million pounds, Fox said in a letter to lawmakers detailing the cost of Britain's involvement in Libya. The latest figures show that British jets and helicopters have flown 200 sorties that fired their weapons between the start of the mission on March 19 and until June 14.

Ahead of his statement, Fox said Britain and others had used "expensive precision weaponry" in Libya in an attempt to minimize civilian casualties.

In March, Treasury chief George Osborne said the campaign would cost "tens of millions, not hundreds of millions" of pounds (dollars).

Fox said Thursday Britain's Treasury has agreed to meet the costs from reserves.