Gordon Brown has ordered all Labour MPs to declare "as soon as possible" details of any relatives they employ.
In a letter to the Speaker, he says he has told Labour MPs not to wait until April, as recommended by the Commons standards committee earlier.
Conservative leader David Cameron has already told his frontbenchers to declare any employed relatives, plus a range of other expenditure.
The initiatives come after a series of revelations about MPs employing family.
The Commons estimates committee announced on Tuesday it was to hold a review of expenses after claims public money was being misused. It is due to report in October.
In a letter to Speaker Michael Martin, the chairman of the estimates committee, Gordon Brown said he welcomed its review, saying a "root-and-branch overhaul of the current system" was needed.
I feel that Brown is implementing this investigation because he is worried about losing his power in Parliament. I think he feels that if members of opposing parties elect family members with similar views, he could very well be voted out of office.
Grade this.