A Liberal Democrat whip has attacked some of his fellow MPs for doing little except "hanging around the chamber waiting for death."

In an interview with the House Magazine, Paul Keetch said he intends to leave Parliament at the next election having become "disillusioned" with the conduct of some members.

"I'm standing down at the next election. From a personal point of view, I will be approaching 50, and if I'm to have another career I will need to get on with it by then.

"To be honest, I have become disillusioned with some of my colleagues in Parliament.

"You look around the House of Commons and see some Members who have been there for 15, 20, 25 years and who are frankly doing nothing, particularly the ones with large majorities. It is not part of my plan to be hanging around the chamber waiting for death.

"Seeing the awful number of MPs in all parties who really should have moved on and done something else in their lives has spurred me on to attempt another challenge," Keetch said.

Keetch also called on leader Nick Clegg to formulate a defining policy to take the Liberal Democrats forward.

He said: "After some uncertain times at the top of the party we now have Nick Clegg as leader, not only for the next election but far beyond it, and that gives us a degree of stability.

"Nick is concentrating on civil liberties and that is right. There is a growing sense of disillusionment in the country with more and more authoritarian government – bigger and tighter government is not a good thing.

"Issues like ID cards, detention without trial – we are a liberal party and we should be strong in standing up for liberal values. The other thing we have to do is find one issue that is a defining Liberal Democrat policy.

"We had it with the penny on income tax for education under Paddy Ashdown, then under Charles we had our opposition to the Iraq war. Now we need to find an issue that really resonates – it might be ID cards, I don't know."