By politics.co.uk staff
Labour's position on Trident is "pretty desperate stuff", according to the Liberal Democrat defence spokesman.
The comments came at the end of the day which saw tit-for-tat attacks from Labour and the Lib Dems on the subject of Britain's nuclear deterrent.
Defence secretary Bob Ainsworth called the Lib Dem position "ridiculous" on the Today programme this morning, after he was reminded Nick Clegg pledged no 'like-for-like' replacement of the nuclear system.
"Nick's position appears to be that he wants to continue to have an independent nuclear deterrent, but he wants a cheap one, and a cheap one would be a vulnerable and ineffective one, that is the fact," he said.
"It's a ridiculous policy."
Nick Harvey shot back for the Lib Dems both on the programme and in statements throughout the afternoon.
"This is pretty desperate stuff from Labour," he said.
"Key figures in the military and defence establishment have called for a rethink on Trident.
"The Labour and Conservative policy of like-for-like replacement of Trident is absurd.
"At a time when the threats to our country have changed dramatically, when President Obama has just warned of the greatest nuclear danger being from terrorist use of nuclear material and when our troops are short on vital equipment in Afghanistan, Labour wants to press ahead with a £100 billion nuclear weapons system designed for the Cold War and won't even consider Trident in the upcoming defence review."
The spat comes on the same day that Labour and the Conservatives desperately tried to reassess the Liberal Democrat threat on the back of Mr Clegg's game-changing leaders' debate performance.
A YouGov poll for the Sun today put the Lib Dems in second place, two points ahead of Labour. Gordon Brown admitted the election race was wide open while David Cameron gave a speech urging voters to give him an emphatic victory to avoid a hung parliament.