Allen Stanford, the Texan billionaire and cricket enthusiast, has refused to co-operate with investigators looking into his alleged $8 billion fraud.

In a filing with a US District Court in Dallas, Mr Stanford invoked the Fifth Amendment, which allows him to remain silent to avoid incriminating himself.

He was responding to a civil case filed by the Securities and Exchange Commission (SEC), America's top financial regulator, on February 19 that accused the entrepreneur and two of his employees of conducting a massive investment scam over many years.

The filing from Mr Stanford said: "I hereby assert my privilege against self-incrimination under the Fifth Amendment to the United States Constitution and decline to testify or provide and accounting, and will continue to decline to testify, provide an accounting or produce any documents related to the matters set forth in the Commission's complaint."

The billionaire specifically noted that he would not provide evidence regarding how he solicited funds from investors, where investors' funds were kept or whether he destroyed documents relating to the alleged fraud.

Mr Stanford, his company's chief investment officer Laura Pendergest-Holt and finance director James Davis are accused by the SEC of paying investors falsely inflated returns from money placed with Stanford Financial Group by new customers. The flamboyant Mr Stanford funded the world's richest cricket prize and was closely connected with the offshore tax haven of Antigua, where his Stanford International Bank was based.

The SEC is expected to file a request to the court tomorrow to extend a freeze on Mr Stanford's and his company's assets while it conducts its investigation.

Sources said that it was common for defendants to use their Fifth Amendment rights when they feared that they may later face criminal charges over their actions.

Mr Davis has also declined to co-operate with the SEC's investigation, while Ms Pendergest-Holt assisted investors but was later additionally charged with criminal obstruction after allegedly withholding information. Her lawyers have said that she is innocent of the charges against her.

Lawyers for Ms Pendergest-Holt said today that investigators working for Ralph Janvey, Stanford Financial Group's court-appointed receiver, raided her home on March 2 and improperly seized personal items including her car keys and family letters.

Jeffrey Tillotson, Ms Pendergest-Holt's lawyer, added that Mr Janvey's lawyers "rummaged through drawers containing personal items of clothing and the defendant's undergarments".

Meanwhile, Mr Janvey today gave instructions to Stanford Financial Group customers on how to retrieve their assets held with the company.

About 12,600 customer accounts held by Pershing, a clearing firm that held most of Stanford Financial Group's funds, have now been released from the freeze affecting the company.

Account holders with balances of $250,000 or less can transfer their accounts to a new account, also with Pershing, which they will be able to access.

Many Stanford customers had complained that they faced financial hardship during the SEC investigation because they were unable to use funds held with the financial company.

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