Alistair Darling was considering increasing VAT to 18.5% to help pay Britain's debt, another data handling bungle has revealed.
A draft version of a document containing details of discussions about increasing the VAT rate in 2011 was published on a government website by mistake.
The VAT information should have been removed before the final version of the document appeared on the Office of Public Sector Information website.
The site offers services to find, use, share and trade public sector information.
Shadow chancellor George Osborne said the document showed Gordon Brown had a "secret plan" to increase VAT permanently after the next election, according to the Metro newspaper.
The revelation comes just a day after chancellor Alistair Darling announced a 13-month reduction in VAT from 17.5% to 15% starting next Monday.
A treasury spokesman said last night that the change to 18.5% was just an option that was considered and later discarded.