Mr Conway's employment of his son prompted the review

A Standards and Privileges Committee report says it should be compulsory to declare employment of family members on the Register of Interests by 1 April.

MPs should also state which relative it is and the type of job, but should not have to reveal the salary, it said.

The report followed the reprimanding of Tory MP Derek Conway over payments made to his son while at university.

He has since had the Conservative whip withdrawn, was suspended from Parliament for 10 days and ordered to repay �13,161.

'Transitional period'

Tory leader David Cameron has already told his frontbench team to declare any relatives they employ by April and urged backbenchers to do the same.

Prime Minister Gordon Brown and Lib Dem leader Nick Clegg have sent out similar messages to their MPs.

We have to change our rules and the House needs to agree that Sir George Young

The committee's recommendations will have to be approved by MPs before coming into force.

While it said relationships should be declared by 1 April, its report added the "relatively short notice may cause legal and contractual difficulties" for some MPs.

The committee's chairman, Sir George Young, told the BBC: "We have to change our rules and the House needs to agree that. We are actually doing this very quickly.

"If you have more transparency, then it will become much more apparent, much more quickly, if a member is employing a relative and there's no evidence of that relative doing any work."

Since the Conway case, the committee said several MPs had come forward to register family members, even though there is currently no requirement for them to do so.

It said any new reporting requirement was "best introduced by the House, rather than through individual initiatives".