Betty Boothroyd, the Speaker of the Commons, is to be asked to investigate whether the rules have been broken. The passes allow holders free access to ministers and early sight of sensitive documents.
At least two dozen people, including Peter Mandelson's part-time office manager and William Hague's entire staff - based at Conservative Central Office - have not declared that they work mainly outside the House.
Some passholders do not even seem to be covered by the rules, which say "gainful" positions should be declared.
A "researcher" for Alan Meale, the Environment minister, does not mention his connection with the Cypriot Brotherhood, a major Labour Party donor.
The list also reveals that about a dozen House of Commons passholders work as commercial lobbyists. Many others have full-time jobs elsewhere but have stayed within the rules by registering their interests.
The revelations will fuel suspicion that little has changed since 1989, when it emerged that Pamella Bordes, who had relationships with a minister and a Fleet Street editor, had been given a Commons pass.
A Sunday newspaper alleged Ms Bordes was working as a prostitute. At the time, a Labour MP said that passes were being handed out "like confetti". But members of the public still have no right to know who is on their MPs' staff.
The register, a copy of which has been obtained by The Independent, is held in the Commons library and is only available to members.
Norman Baker, the Liberal Democrat MP for Lewes, is writing to Ms Boothroyd and to the new Parliamentary Commissioner for Standards, Elizabeth Filkin, who takes over when Sir Gordon Downey retires at the end of this month. He will ask them to decide on whether the rules are being applied strictly enough.
"There appears to be a case for investigation. It is important that MPs, particularly those in positions of power, operate the highest standards," he said.
Everyone who applies for a researcher's or secretary's pass on behalf of an MP must say whether they have any other "relevant gainful occupation" which might be helped by privileged access to the House. A check against the Commons' internal phone directory shows that only about half have a desk there. While some may have moved on and others work in constituency offices, many have jobs outside Parliament.
Haris Sophoclides, who was given a pass by Mr Meale, declares that he is managing director of J&P (UK) Ltd, a civil engineering company, but does not mention that he is president of the powerful Greek Cypriot Brotherhood, which gave more than pounds 5,000 to the Labour Party last year.
Mr Mandelson has given a Commons pass to Clive Russell, Major League Baseball's director of operations in London.
A spokesman for the Secretary of State for Trade and Industry said Mr Russell worked part-time for him keeping office costs and other clerical matters in order. He had asked the House of Commons pass office whether he needed to declare his other job and had been told he did not.
Eleven members of MrHague's office staff, which has decamped to Conservative Central Office, are listed on the register but do not declare that they are based at party headquarters. The party says they are still paid from the public purse as workers for the Leader of the Opposition.
In a separate development yesterday, it emerged that the Senior Salaries Review Board, which oversees MPs' pay and allowances, is looking at whether the system of expenses in the Commons should be tightened up. MPs can claim up to pounds 47,000 for their offices, plus tens of thousands in expenses.Reuse content