Former top tax official Dave Hartnett has landed a job with a leading accountancy firm a year before the expiry of Whitehall restrictions that stop him lobbying the Government and advising UK companies on cutting tax bills.

Mr Hartnett was sharply criticised by MPs over "sweetheart" deals with major corporations when he headed HM Revenue and Customs.

He will work one day a week for Deloitte – whose clients include Vodafone and Starbucks – as an adviser to foreign governments and tax regimes.

His appointment was subject to approval by David Cameron and the advisory committee on business appointments on condition he does not advise firms whose cases he was involved with while at HMRC.

He has also been told he cannot work on how to mitigate or avoid UK taxation for Deloitte's clients and he cannot lobby the Government on behalf of his new employer.

But the restrictions will go in July 2014, two years after Mr Hartnett left HMRC.

Deloitte said he would work as a consultant for the firm "advising foreign government and tax administrations, primarily in the developing world".

It added: "He has significant experience in advising such countries on the development of effective tax regimes, necessary to ensure their continued economic growth."

A spokesman said the role would not involve advising private-sector clients. There was no intention for the role to change in a year's time.

MPs criticised HMRC when Mr Hartnett's was in charge over its "unduly cosy" relationship with major firms .

In a report in December 2011, the public accounts committee expressed concerns over banking giant Goldman Sachs being allowed to skip a multimillion pound interest bill on unpaid tax.