Mr Conway also denounced “homophobic” media reports concerning his elder son's Henry’s sexuality and his work as a party promoter.

He said he had known “for a long time” that Henry was gay and always supported him. He described his son as “a lovely boy”.

Mr Conway also rejected allegations that he employed another researcher, Michael Pratte, because he was a friend of his sons. In fact, Mr Pratte met Freddie and Henry only after joining his office, he said.

The Old Bexley and Sidcup MP said he could understand public outrage at reports of him using taxpayers’ money to employ family members as “the public believe all politicians have their snouts in the trough”.

But he made clear he suspected some of his parliamentary critics had ulterior motives.

He accused Labour of wanting to take the heat off itself because of pressure on Gordon Brown over Alan Johnson and Peter Hain.

Mr Conway denied that MPs were overpaid for their work, pointing out that he took a cut in salary when he left the £80,000-a-year post of chief executive of the Cats Protection League to return to the Commons in 2001 and will receive a pension of £24,000 when he retires.

He suggested a fair salary for a backbench MP would be £80,000 to £100,000, rather than their current £60,000.

His wife Colette, who works as his Commons secretary, told the newspaper she supported her husband and sons whom she said had done nothing wrong.

Mr Conway announced last week that he will stand down as an MP at the coming General Election, after David Cameron withdrew the Conservative whip.

He is facing a possible second inquiry into the job he gave his elder son Henry, while Scotland Yard are considering a demand for a police probe to examine allegations of fraud.