Sutton Coldfield MP is facing a possible parliamentary standards probe after apparently intervening on behalf of a cocoa magnate who had donated £40,000 to his political office.
International Development Secretary Andrew Mitchell, Conservative MP for Sutton Coldfield, stepped in after businessman Anthony Ward - known as "Chocfinger" - approached him for help over a trading ban that had been imposed on his firm in Ghana.
Labour MP John Mann said he had referred the minister's case to parliamentary standards commissioner John Lyon. Mr Mitchell denies any wrongdoing.
According to documents obtained by the Sunday Times, Mr Ward wrote to the new minister weeks after the general election asking him to lobby against the restriction "at a presidential level".
Mr Mitchell apparently phoned the British high commissioner in Ghana on the matter, even though it was strictly outside his department's remit. His officials also contacted the Foreign Office to say that the partial ban on Armajaro Holdings - imposed amid allegations that one of its contractors had been smuggling cocoa - required "urgent attention".
Foreign Office minister Henry Bellingham subsequently lobbied the vice-president of Ghana on behalf of Mr Ward's company.
The ban is now said to have been lifted in all but one of the country's districts.
Mr Mann said: "The report that Andrew Mitchell lobbied on behalf of 'Chocfinger' raises serious questions to answer about the secretary of state's conduct. Was Mr Mitchell acting in the best interests of the British government or an individual that has subsidised his parliamentary office?
"I have personally referred him to the parliamentary commissioner for standards to ensure that the British people get answers to these questions."
The Commons register of financial interests shows Armajaro Holdings gave some £40,000 to Mr Mitchell's parliamentary office to support his work as shadow international development secretary between August 2006 and December 2009.
A spokesman for Mr Mitchell's Department for International Development said: "The letter from Armajaro was dealt with in accordance with normal ministerial procedures and it was immediately made clear that the Conservative Party had previously received donations from the company, as the documents released under FOI make clear. The matter was referred to the FCO through the normal channels."