Derek Conway, who was suspended from the Commons and thrown out of the Conservative parliamentary party after a scathing report last week, insisted he had done nothing wrong in giving sons Freddie and Henry jobs as researchers and rejected claims that they did little or nothing for the £80,000 they were paid.

Mr Conway spoke out as pressure grew on MPs to accept external audits of their expenses claims, which last year totalled £87 million - an average of £137,000 each.

The Commons Members Estimate Committee, chaired by Speaker Michael Martin, is due to meet to discuss a proposal for the National Audit Office to conduct spot checks on up to 10% of MPs' expenses claims to ensure they are genuine.

Sleaze watchdog Sir Christopher Kelly, the chairman of the Committee on Standards in Public Life, said MPs should accept greater openness about their finances in order to shake off public perceptions of impropriety.

The reputation of MPs had "clearly not improved" since the anti-sleaze measures brought in after a string of scandals under John Major's 1990s administration, he told The Observer.

And he added: "What I think Members of Parliament need to consider is whether or not they get greater protection from false accusations that they are behaving improperly if there is actually a greater element of transparency."

After the leaders of all three major parties called on MPs to make clear if they employed relatives, it emerged that more than a quarter of the House of Commons - up to 177 MPs - do so.

Labour sources said 90 to 95 of their MPs employ relatives - often spouses or children paid to work as secretaries or assistants - while the figure for Tories was 70 and for Liberal Democrats 12.

Mr Conway insisted there was nothing wrong in keeping parliamentary jobs in the family. In his first interview since Monday's Commons Standards and Privileges Committee report on his employment of Freddie, he told the Mail on Sunday: "I am not a crook... I still believe I have done nothing wrong."