The BBC's Laura Trevelyan: "Mr Ashcroft is a controversial figure"

The Belize-based billionaire issued a statement in which he said that if the DEA did have a file "it obviously contains no facts that would sustain a charge" since no charge had been made.

The agency had not even attempted to contact him, he added.

Mr Ashcroft said: "I make this categorical statement: I have never been involved in drug trafficking or money laundering.

"My business affairs are entirely proper and no amount of smear, rumour or innuendo will alter that fact."

Tory leader William Hague: "There is a lot of smear and lot of innuendo"

The Conservatives this week claimed that Mr Ashcroft, who has donated millions of pounds to the party, had been the victim of a Government-inspired smear campaign.

Mr Ashcroft hinted that commercial and political rivals were responsible for the wave of "rumours" about his business affairs.

Fresh allegations

His statement came after the Saturday edition of The Times newspaper printed further allegations about him.

The newspaper says that Mr Ashcroft came under scrutiny as part of four separate investigations dating back 10 years or so.

But Mr Ashcroft said: "I am a tough and determined man and I have made many enemies over the years.

Michael Ashcroft is now a national of Belize

"I also have many aggressive competitors and am involved in politics which has always attracted dirty tricks and smear tactics.

"Now I can add The Times to my list of enemies. However, being an enemy does not make you right, simply hostile."

He added: "I set up Crimestoppers in 1987. I am the chairman of trustees. I have given this organisation millions of pounds over the last 12 years and it has been responsible for 29,000 arrests.

"Given these facts - as opposed to rumours - I clearly do not condone wrongdoing."

On the DEA file reports, Mr Ashcroft said: "If such a file exists, and I have no evidence that it does, obviously it contains no facts that would sustain a charge as there has been no charge and the DEA has never even made any attempt to contact me."

Support from Belize

Earlier this week, it was alleged that Mr Ashcroft approached the Conservative government in 1994, to ask them to persuade the government of Belize not to change its banking system.

Foreign Office files about Mr Ashcroft were leaked to the newspapers.

But the government of Belize, for whom Mr Ashcroft is ambassador to the United Nations, dismissed speculation about the businessman.

In a statement, Belize said the newspaper stories had a "clear partisan-political agenda" and contained "reckless misrepresentations concerning Belize as a financial services jurisdiction".

The statement continued: "It is regrettable that a sovereign nation and its economy should be smeared in so irresponsible a fashion simply to fuel the needs of British domestic politics."