Mr Levitt said: "I have no income from employment other than my salary as an MP.

"If I were to have a second job I could not do the 60 to 70 hours work each week that I presently commit to all facets of my work."

He criticised those MPs who earn large sums of money through additional jobs: "MPs who earn tens of thousands of pounds doing jobs outside Parliament cannot be doing justice to either their employer or their electors.

"While it is right for MPs to have interests outside Parliament, as well as having a non-Parliamentary background, it is cynical and wrong to accept thousands of pounds for a few hours of work each year, as some do."

Mr Levitt revealed that he holds two unpaid positions outside Parliament, one as the Chair of Trustees of the Community Development Foundation (CDF). This is a government appointment, although the CDF is both a non-departmental public body and a charity

"My work for the CDF takes five or six days in total each year.

"I am also the patron of a student volunteering charity, Read International, which builds links between schools and universities in Britain and schools in Tanzania.

"This work has involved up to two days per year, to date."

The High Peak MP added: "I occasionally complete questionnaires for market research or polling organisations which often pay a fee of £25 or £50.

"This is usually directed to a local or national charity.

"Even though I am not the personal beneficiary of these payments, the new rules rightly require me to declare them."

MPs had to declare their income from all sources and how much time they spend earning money outside Parliament by July 1.

The register will be published shortly.