The Liberal Democrats' Treasury spokesman, Vince Cable, has said that said cuts of between £80 and £100bn in public spending are needed during the next parliament to rebalance the UK's finances.

But, speaking on the programme, he warned that they should not begin immediately. "To rush in now with big cuts in services, people losing their jobs would disastrous", he said.

"We're still in the middle of a recession, there are large numbers of people losing their jobs and simply contracting government spending, increasing taxation at this moment in time runs the risk of getting us into a deeper recession, which means that the deficit is even worse."

He comments come as the BBC learns that the Chancellor, Alistair Darling, has begun meeting senior Cabinet colleagues to discuss ways to cut public spending, with ministers being asked to identify possible savings but, as yet, without any targets to meet.