The Tories are engulfed in controversy after the Cabinet Office minister Oliver Letwin admitted throwing official paperwork in park bins near No 10 Downing Street.

Letwin is the subject of an investigation by the information commissioner into a breach of data protection laws after being photographed by the Daily Mirror disposing of private letters and other papers.

The paper claims Letwin threw away more than 100 documents in St James’s Park between September 7 and October 10, including correspondence on terrorism and national security.

But Letwin’s office claims the documents held no sensitive information.

According to the paper, the documents included correspondence that touched on subjects such as al-Qaeda’s links in Pakistan, the government’s flagship Big Society agenda and the future of the Forensic Science Service.

In one letter reportedly thrown away, Sir Malcolm Rifkind – chairman of the ISC – is urged by a fellow Tory MP to revamp the body to “bolster public confidence in its work and in Parliament’s ability to hold intelligence services to account”.

The letter’s author Andrew Tyrie – chairman of the all-parliamentary committee on extraordinary rendition – notes that their correspondence is “personal and confidential”.

Labour have accused Mr Letwin of “cavalier” behaviour and urged Cabinet Secretary Sir Gus O’Donnell to look into whether the “strict procedures” for dealing with government documents had been broken.

However, Sir Malcolm – a former foreign secretary – told the BBC the letter “did not amount to a row of beans in terms of secrecy” and was just correspondence between two backbenchers.

A Cabinet Office spokeswoman said: “Oliver Letwin does some of his parliamentary and constituency correspondence in the park before going to work and sometimes disposes of copies of letters there.

“They are not documents of a sensitive nature.”

The Commissioner has the power to fine organisations and individuals up to £500,000 if it found anyone had suffered serious distress as a result of data protection breaches.

Meanwhile, the Tories are being scrutinized on another front, after more revelations emerge about Defence Secretary Liam Fox’s relationship with Adam Werritty.

Top Tories are calling on Fox to step down after it emerged Fox’s tycoon friends paid for Werrity to fly around the world with him, including a corporate intelligence company and a billionaire who lobbies for Israel.

Senior cabinet members believe Fox’s position is becoming increasingly untenable after he admitted he met Werritty on 18 different foreign visits over the past 16 months – raising questions about who his best man and former flat mate was acting for in their private meetings.

Some £147,000 was paid into the bank account of Pargav Ltd, a not-for-profit company set up by Werrity, Dr Fox’s self-styled adviser, to cover the costs of first class air travel and top hotels.

Details of Pargav’s accounts, revealed last night by the Times, show that a similar amount was paid out to fund Mr Werritty’s expenses.

A further £50,000 was also transferred into the accounts of two other companies linked to Mr Werritty.

In further damaging revelations, it emerged that a U.S. defence lobbyist also acted as Dr Fox’s unofficial ‘adviser’.

John Falk, a U.S. consultant who has raked in tens of thousands of dollars advising firms how to win military and security contracts, described himself as an adviser to the Tory politician on his website.

Downing Street told a daily media briefing in Westminster this morning that Dr Fox continued to have the Prime Minister’s confidence.

A spokeswoman declined to say whether the terms of reference of the Cabinet Secretary’s inquiry were being extended to take into account the fresh allegations, saying only that Cabinet Secretary Sir Gus O’Donnell, who is undertaking an inquiry into the matter would “look into all the

unanswered questions” and ascertain whether the ministerial code of conduct has been breached.

“There are lots of questions which do draw concern, which is why this inquiry is ongoing.” the spokeswoman said.