A senior adviser to David Cameron has quit Downing Street to become a lobbyist for Wonga, the controversial payday lender, renewing concerns about the "revolving door" between government and business.
Jonathan Luff, the Prime Minister's adviser on digital strategy, has been given clearance to start work immediately at the company, which has been criticised for charging annual interest rates of up to 4,000 per cent.
Wonga confirmed that Mr Luff, a career diplomat with the Foreign Office before being seconded to Downing Street, would head the company's government affairs team.
The company is fighting regulatory intervention in the payday lending market which threatens to limit the activities of participants, by giving borrowers, often the most vulnerable families, greater protection.
Earlier this year Wonga was censured by the Office of Fair Trading for employing "aggressive and misleading" debt collection practices. It also emerged recently that Wonga representatives paid £1,500 a head to meet ministers at a "speed-dating" policy event at the Conservative conference.
Stella Creasy, the Labour Co-operative MP for Walthamstow and a campaigner for tougher restrictions on payday lending, called on the Government to confirm that Mr Luff would not be allowed to lobby ministers on Wonga's behalf for two years, as regulations demand.
Ms Creasy said: "Wonga is making massive profits from preying on consumers in Britain's poorly regulated consumer credit market. They have used these profits to target our football clubs and Saturday night TV, and now they are targeting the highest echelons of government."
Wonga said Mr Luff's appointment was fully compliant with the Advisory Committee on Business Interests, which scrutinises job moves by civil servants to the private sector but has no power to block a person taking a position.
A spokesman said it was "delighted" that Mr Luff, who for the past two years has worked on the "Great" campaign to promote British excellence overseas, was joining the company.