Gordon Brown remains committed to extending the pre-charge detention period for terror suspects, Downing Street insisted yesterday.

Amid claims that ministers have given up hope of getting the legislation through the House of Lords, the Prime Minister's spokesman said his position had not changed.

The legislation faces severe opposition in the Lords. Mr Brown's spokesman refused to "get into hypotheticals" about whether the government would use the Parliament Act to override the Lords.

But he said: "The Prime Minister is clear that pushing ahead with the 42 days legislation is the right thing to do, given that the House of Commons has expressed its will."

Labour MP David Winnick urged the premier to give up on the proposal in the interests of the country and the party. "The last thing we need is for the Parliamentary Labour Party to be divided at a time when there is no necessity to do so," he said.

The 42-day measure was deemed "muddled" and "ill-advised" by the cross-party Lords Constitution Select Committee.

Last week a key Council of Europe committee expressed "considerable concern".

Andy Hayman, the former Scotland Yard assistant commissioner who backs the need for the change, yesterday said the proposals were "not fit for purpose: they are bureaucratic, convoluted and unworkable".

Shadow Home Secretary Dominic Grieve said: "We know this policy is unnecessary, unjustified and unworkable."

Liberal Democrat home affairs spokesman Chris Huhne said: "Britain's hard-won civil liberties are too important for political games."