They include Jacqui Smith, the Home Secretary, Hilary Benn, the Environment Secretary and Caroline Flint, the housing minister. Others included Sir George Young, chairman of the Standards and Privileges Committee, and Sir Stuart Bell, one of the senior MPs reviewing parliamentary expenses.

All listed their relatives in the first publication of the Register of Members' Interests to include such details in the wake of the Derek Conway scandal.

Mr Conway was stripped of the Conservative Party whip and suspended from the Commons for ten days for overpaying his son out of his expenses.

There is no suggestion that any other of the 106 MPs to declare their interests since 1 April have broken the rules. The declaration of relatives paid out of MPs' expenses has only been voluntary since 1 April, although party leaders have urged their MPs to do so as soon as possible.

It will not become compulsory until 1 August, when it will include all relatives paid more than 1 per cent of an MP's basic salary – or £618 a year.

Mr Conway declares that he still employs his wife, Colette Conway, as an "office manager/executive secretary". The pay range for such a role is from £21,320 to £40,052.

Ms Smith lists her husband, Richard Timney, as a "senior research/parliamentary assistant", who will be earning between £27,780 and £40,052. Sir Stuart employs his wife, Margaret Bell, as "office manager".

Ms Flint's husband, Phil Cole, occupies the same position in her Commons office as does Sir George's daughter, Camilla Young, in his. Mr Benn's wife, Sally Clark, is listed as his "research/parliamentary assistant", which entitles her to between £14,212 and £34,240.

Among other prominent politicians, David Davis, the shadow home secretary, employs his wife, Doreen Davis, as "executive secretary".

Peter Hain, a former work and pensions secretary, lists his mother, Adelaine Hain, as "part-time secretary". Michael Howard, a former Tory leader employs his wife, Sandra Howard, in the same position.