Britain's International Development Minister Alan Duncan on Friday faced scrutiny over his links to an oil firm which secured rights to provide Libya's rebel National Transitional Council (NTC) with fuel.
Duncan devised Britain's plan to starve Moamer Kadhafi of oil while keeping the rebels supplied, but faced "serious questions" over the process whereby Swiss-based giant Vitol gained the NTC contract.
Former oil trader Duncan has close past links with Vitol president Ian Taylor, who has donated hundreds of thousands of pounds to the Conservative party.
Opposition MPs demanded to know whether the government's covert "Libyan Oil Cell" had set up the $1 billion deal.
Labour MP John Mann called for an inquiry and urged the government to reveal whether senior civil servant Gus O'Donnell had approved the "extraordinary deal".
"This is the worst kind of government giving a company that paid Alan Duncan a secret deal," Mann said. "It is just like the way Arab dictators behave. Or the way some of the American deals were done in Iraq after the war."
Prime Minister David Cameron's office said there had been no wrongdoing, but confirmed that Duncan had met Vitol in an attempt to avoid a crisis if rebel-held areas ran out of fuel.
"The government did not lobby on Vitol's behalf," a spokesman said. "The company had an existing commercial relationship with the NTC and we are confident that the correct procedures were followed."