David Cameron has asked for a report on the initial findings from the internal Ministry of Defence investigation into Liam Fox to be on his desk on Monday, Downing Street said on Saturday.
The defence secretary is under severe pressure from the media and Labour over his working relationship with his close friend Adam Werritty, who despite having no official government job or security clearence accompanied Fox on foreign trips, set up meetings for him and described himself as his adviser.
On Friday Fox himself ordered an in internal Ministry of Defence inquiry into whether he had broken the ministerial code. That inquiry is being carried out by Ursula Brennan, the department's permanent secretary. She originally expected the investigation to take two weeks. Her report will be examined by the most senior civil servant, Sir Gus O'Donnell.
The move by Downing Street to bring forward the timetable could be seen as an attempt to take control of the situation and ensure the controversy does not drag on for weeks.
A spokesman for No.10 said: "The prime minister has asked the cabinet secretary to examine the initial findings of the MoD permanent secretary review and to report his conclusions to him on Monday.
"While the facts are being estabished the prime minister remains supportive of the defence secretary".
The code states that ministers "must ensure that no conflict arises, or could reasonably be perceived to arise, between their public duties and their private interests, financial or otherwise".
Werritty was best man at Fox's 2005 wedding and according to the Daily Telegraph also lived rent free in the North Somerset MP's taxpayer-funded property in 2002-2003.
Labour MP John Mann has said that he has referred Fox to the Parliamentary Commissioner for Standards over the issue.
He said that if Fox should follow the example of former Labour MP Ian Gibson who resigned from Parliament in an identical situation when he had allowed his daughter to live tax free in a taxpayer funded flat.
Mann told the Huffington Post UK that the utility bills of the flat were paid for by the taxpayer through parliamentary expenses system and Werritty would have unfairly benefited from that by "switching on the lights".
"Never mind resigning as defence secretary, he should resign from Parliament immediately," he said.
It has been reported that Werritty set up a June meeting in Dubai between Fox and a company who wanted to sell communications encryption technology to Britain.
Werritty has been accused of distributing business cards that said he was an adviser to Fox even though he had no formal role. Fox has since said he has made it "very clear" to Werritty that it was "unacceptable to carry a card saying that he's a personal adviser."
It is also said that Werritty ran the ran the charity Atlantic Bridge, which promoted UK-US relations, from inside Fox's parliamentary office. Atlantic Bridge has since been closed down following concerns that it was too party political.
Defending himself to the Sunday Telegraph, Fox questioned the motivations of those accusing him of wrongdoing.
"I have absolutely no fear of complete transparency in these matters. I think there are underlying issues behind these claims and the motivation is deeply suspect," he told the paper.
In a uncomfortable piece of parliamentary timetabling for Fox, he is due to appear before MPs for an hour on Monday at defence questions.
Labour's shadow defence secretary Jim Murphy is expected to ramp up the pressure on his opposite number by demanding he come to the Commons to make a separate statement on the allegations.
"There should be a full statement by the Secretary of State on Monday in the House of Commons," he told Sky News.
"If he doesn't volunteer to make a full statement I will seek to summon him. An inquiry is important but so too are direct answers."
The controversy has undermined Fox's trip to Libya, in which he announced a £500,000 funding package and extra military expertise to help Libya's new government.