The Labour MP for Nottingham South, Alan Simpson, said Labour MPs and members would be horrified if Lord Ashdown became a member of a Labour government.

He said: "The party would be livid if this happened. We need a Lab-Lab pact not a Lib Lab pact. Brown ought to make overtures towards the bulk of the Labour Party which is to the left of New Labour. The truth is that is where most of the electorate is to be found these days."

The former defence minister Peter Kilfoyle warned: "In the Parliamentary Labour Party this will be seen as a snub to many people who have hoped there would be a change of direction.

"I'm very concerned about this. I'm a Labour party person and I want nothing to do with the Lib Dems. They are our opponents in the North of England and we don't have any ideological common ground with them."