The true extent of Cherie Blair's financial gains - which include free overseas flights and payment for charity speeches - may have to be made public under plans to force MPs to register the business interests of their partners.
A review of the rules being carried out by Parliament's sleaze watchdog, the Committee on Standards in Public Life, is expected to look at whether to tighten the rules so that the jobs, investment portfolios and business interests of MPs' husbands and wives are made public.
MPs have also called for a review of the rules to stop colleagues using air miles collected from official flights for family holidays.
Ministers are governed by rules forcing them to use their air miles for business use. Some, such as Tessa Jowell, the Secretary of State for Culture, give them to charity. But backbench MPs are allowed to rack up air miles gained from travelling to and from the Commons for personal use, without registering them.
"MPs should not be using air miles for their own benefit," said Norman Baker, Liberal Democrat MP for Lewes. "The rules should be the same for MPs and ministers."
Sir Philip Mawer, the Parliamentary Commissioner for Standards, is preparing to review the rules on what MPs must record in the public register of members' interests. The examination of the rules would also look at the issue of air miles.
"There will be a review of the rules on registering and declaring interests - that would be the context in which it needs to be done," said a spokeswoman for the standards watchdog.
Mrs Blair has been under mounting criticism to disclose the fees she has gained from making speeches and the free flights to charity events. And earlier this year, she was forced to cancel a gala opening of a shopping centre owned by a Malaysian billionaire, following criticism of her role.
In the latest register of members' interests, the Prime Minister declared a series of speeches Mrs Blair gave in the US, Australia and New Zealand.
He confirmed they included "some discussion of my wife's life in No 10 Downing Street". He also included royalties from Mrs Blair's book The Goldfish Bowl, which he said "makes reference to her life in No 10 Downing Street". Currently, MPs only have to register financial gains from spouses if they are related to their role as MPs.
But MPs have called for fuller disclosure, and there is growing pressure in Parliament for all financial interests of wives and husbands to be listed - to prevent any conflict of interest arising in political life.
"There is a good case for extending registration to immediate family members. It's not just the reality of corruption; it's the perception, and there have been a number of questions raised in different areas recently about this," said Adam Price, Plaid Cymru MP for Carmarthen East & Dinefwr. "If everything is transparent, it's just easier."Reuse content