Defence Secretary Liam Fox’s political career hung in the balance on Monday as he prepared to face a parliamentary grilling over his friend’s reported involvement in government affairs.

Fox on Sunday responded to accusations that he had an inappropriate working relationship with friend Adam Werritty, saying he was “very sorry” for “giving the impression of wrongdoing”.

In a statement he also accepted it was “a mistake to allow distinctions to be blurred between my professional responsibilities and my personal loyalties to a friend”.

But the minister said he would answer “all questions” about Werritty’s involvement in government business, including Afghanistan and Libya, during the scheduled House of Commons defence questions on Monday.

Fox insisted that “at no stage” did he provide classified information or briefings to Werritty — who has no official government role — or assist the businessman in his commercial endeavors.

The under-fire minister also revealed he had apologized to Prime Minister David Cameron for meeting a commercial supplier without the presence of an official, and was working to legislate against such meetings in the future.

Cameron on Saturday said that Fox had his “full confidence” despite the allegations about Werritty, who was best man at Fox’s wedding.

But hours later Downing Street said Cameron wanted a preliminary report setting out the facts by Monday and was not prepared to wait until an internal Ministry of Defence (MoD) inquiry reports back in a fortnight.

Fox, who visited Libya on Saturday, ordered the MoD inquiry on Friday into claims that Werritty had privileged access to him despite having no official role or security clearance.

Fox stopped short of apologizing for the nature of his relationship with Werritty, and regretted only that he “may have given the impression of wrongdoing” and “given third parties the misleading impression that Werritty was an official adviser”.

The Daily Telegraph newspaper reported on Monday that Fox had used public funds to pay Werritty as a parliamentary researcher.

The row escalated on Saturday when The Observer newspaper carried footage on its website of Werritty apparently attending a meeting between Fox and Sri Lankan President Mahinda Rajapakse in London in 2010.

The Telegraph on Monday also claimed that Werritty had acted as Fox’s personal envoy to the Asian nation and had organized meetings with senior ministers.

Other newspapers reported that Werritty had brokered a meeting in Dubai in June between Fox and the Porton Group, a company hoping to sell phone call encryption technology to the British military.

Porton chief executive Harvey Boulter discussed with Fox whether British troops in Afghanistan could use the technology to call home without being detected by the Taliban, the Financial Times said.

The Conservative lawmaker argued the Dubai meeting came about by chance while he was on a stopover from Afghanistan.

Boulter called this claim “kind of ridiculous” in comments published in Monday’s Guardian newspaper.

“It’s a bit like me bumping into you in a pub in London and buying you a beer and saying ‘oh by the way can I meet the owner of the paper’ and you saying ‘oh sure’, come on,” he said.

The defence chief said Sunday he had “learnt lessons” from the affair and that he would take greater care in the future to protect himself and the government from accusations of wrongdoing.

Labour lawmaker Jim Murphy, the shadow defence minister, said Sunday he had written to Cameron calling for a full investigation, highlighting “several shortcomings” in the current probes.

“The terms of reference are narrow and simply inadequate in light of the evidence that has come to light,” he added.

“It is important that the breadth of this inquiry matches the severity of the accusations.”