The top-up to MPs' current £61,820 salary would be worth about £24,000 after tax - approximately matching the maximum claim under the Additional Costs Allowance (ACA) this year.

The move, one of three options to be put before MPs by an internal review of parliamentary expenses headed by Commons Speaker Michael Martin, would effectively remove the onus on MPs' to justify their expenses claims and hand extra cash to those who do not currently claim the full amount.

The typical MP would be £4,500 a year better off as the average claim under ACA is £19,500.

But it is likely to run into fierce opposition following recent abuses of the expenses system and voters' scepticism about the pay and perks available to their Westminster representatives.

Less controversial alternatives to the £40,000 package - reported in a Sunday newspaper - include a per diem allowance corresponding to MPs' attendance in the Commons.

That would be subject to a similar upper ceiling of about £24,000, again without the need to submit receipts in justification for costs legitimately incurred staying in London.

A third option would see the ACA retained but with more rigorous audits of claims.

The Members' Estimate Committee, which set up the review following the scandal over MP Derek Conway's overpayment of his son out of his expenses, is due to report its recommendations imminently.

They will be discussed in the House of Commons on July 3.