Hague's camps for refugees would cost £2bn

William Hague's tough line on immigration was dealt a blow yesterday with the release of figures indicating the cost of keeping all asylum-seekers in secure detention centres would be at least £2bn.

Government figures said that the centres, which are a key part of the Conservatives' asylum policy, would cost £1.68m to start up and a further £420m a year to run.

The Liberal Democrats seized on the figures, which were given in a written parliamentary reply. Simon Hughes, the party's Home Affairs spokesman, said: "The start-up costs of William Hague's policy show that it was not a properly considered initiative. This was not a realistic policy but irresponsible politics in the middle of an election campaign."

Mr Hague's rhetoric on asylum led to accusations by the British National Party that he was stealing its policies. But the Tory leader's focus on asylum-seekers has put Labour on the defensive.

In response to the figures, the Tories stressed that asylum support costs amounted to £600m last year, significantly more than the £420m needed annually to run the secure detention centres.

Party sources said the figures also failed to take account of the savings that would inevitably occur on asylum support costs if the policy was implemented. A Tory source added: "These figures are misleading because they also failto reflect that the policy would act as a deterrent to asylum-seekers to come to Britain."