Mrs Spelman insists she acted within the rules over expenses
Tory chairman Caroline Spelman, who is under fire for paying a nanny with MP's funds, was making the payments for longer than she previously stated.
The Meriden MP told reporters she paid Tina Haynes to look after her children and do secretarial work for a "short term period", between 1997 and 1998.
But it has emerged that Ms Haynes was on parliamentary pay until March 1999.
MPs are not allowed to use their pay for anything private. Mrs Spelman says she did not break any of the rules.
'Within the rules'
Childcare is counted as non-work related for an MP, and therefore it would be an unacceptable use of public funds to pay for a nanny.
But Mrs Spelman denied she had been wrong to use public funds to pay for Ms Haynes, saying she had done secretarial work so it had been "entirely within the rules".
The Parliamentary watchdog is currently considering whether or not to launch an inquiry Mrs Spelman's behaviour.
A statement from John Lyon's office has said it would be "exceptional" for him to probe a matter dating back seven years.
The Conservatives are yet to comment on the latest development.