The wealthy private backers who funded Liam Fox's close friend included a private intelligence company and an investor who lobbies on behalf of Israel, it has been claimed.

It had been reported by the BBC that Adam Werritty had been able to join the defence secretary on several foreign trips thanks to people who believed he could be relied upon to "champion support for Eurosceptic, pro-American and pro-Israeli policies" in Fox's presence.

Now the Times has said that the backers included G3 Good Governance Group, a strategic advisory company, and venture capitalist Jon Moulton.

Another backer is said to be Poju Zabludowicz, the chairman of the Britain Israel Communications & Research Centre (BICOM) -- an organisation that lobbies the government on behalf of Israel.

BICOM describes itself as "providing resources to individuals and organisations in Britain who share BICOM's agenda to promote a better understanding of Israel".

According to the paper the backers contributed towards the £147,000 paid into the bank account of a not-for-profit company that Werritty owned.

The Daily Telegraph meanwhile has reported that Fox failed to declare that he and Werritty attended a £318 per-person meal in Washington DC with defence industry representatives.

Earlier this week the Ministry of Defence released a list detailing the 18 occasions on which Fox and Werrity met overseas. The event in the Mandarin Oriental hotel was not included.

And the Daily Mail has said Fox also had close links with John Falk, an American consultant who made his money advising firms how to win military and security contracts.

According to the paper, Falk, who is said to have links to controversial US defence firm Blackwater, described himself as an "adviser to Dr Liam Fox MP" while Fox was shadow defence secretary.

A spokesperson for Fox told the Daily Mail: "John Falk has never been an adviser to Liam Fox MP".

The allegation could be damaging as it suggests a defence industry lobbyist was passing himself off as an adviser to Fox.

Today's revelations will only serve add to the pressure on Fox who has struggled to explain why his close friend presented himself as his adviser even though he held no official government role.

Fox does officially employ three special advisers who are permitted to undertake political activities, unlike civil servants. Many have questioned why he did not simply appoint Werritty to one of those positions if he valued his advice.

Before these latest allegations shadow defence secretary Jim Murphy has said Labour was concerned that Fox had bypassed official procedures available for appointing political advisers and the transparency that comes with that.

"The continuous allegation and speculation is damaging for the character of this government and for a defence secretary who has important public duties," he said.

"Our concerns centre on financial propriety, breaches of the Ministerial Code, apparent avoidance of the civil service and a potential conflict between public and private interests."

David Cameron has said he is waiting on an official report from the cabinet secretary Sir Gus O'Donnell into Fox's conduct before he makes any decision on his defence secretary's future.

Speaking on the BBC's Question Time on Thursday, his cabinet colleague Andrew Lansley said people should wait for the results of Sir Gus' inquiry before jumping to conclusions.

"I work with Liam, I've known Liam for a long time, I think he's been an excellent defence secretary," he said.