A US federal judge has ruled that Texan billionaire Allen Stanford is unfit to stand trial at present over accusations he led a $7bn (£4.5bn) fraud scheme.

Mr Stanford is facing trial over allegations that he ran a pyramid scheme based in Antigua which defrauded investors.

He has pleaded not guilty to fraud, conspiracy and obstruction.

District Judge David Hittner ruled that Mr Stanford did not have the present mental capacity to assist his lawyers.

But he ordered Mr Stanford to undergo treatment at a US prison hospital for an addiction to an anti-anxiety medication, and also receive additional psychiatric testing.

"The court finds Stanford is incompetent to stand trial at this time based on his apparent impaired ability to rationally assist his attorneys in preparing his defence," Judge Hittner wrote in his ruling in Houston, Texas.

"The court's finding that Stanford is incompetent, however, does not alter the court's finding that Stanford is a flight risk and that no combination of conditions of pretrial release can reasonably assure his appearance at trial," he added.

The charges against Mr Stanford capped a rapid fall from grace for a man who had shot to prominence in the UK and the Caribbean for his lavish sponsorship of cricket.