Allen Stanford's business empire is being investigated by the Financial Industry Regulatory Authority, the Securities and Exchange Commission and the Florida Office of Financial Regulation in the USA.

Stanford Investment Bank has $8.5 billion in assets and 30,000 clients. It is the interest rates offered to clients which have attracted the most concern, with some analysts pointing out that they are well above the industry norms.

A Stanford spokesman dismissed the reports. "This is a rehash of old gossip and unsubstantiated allegations," he said. "The Stanford Financial Group is rigorously managed and fully compliant with all US regulations. All three agencies have stated to us that they were visiting our offices as part of routine examinations."

Bloomberg News published what it claimed was a leaked email from Stanford to his staff. "We are all aware that former disgruntled employees have gone to the regulators questioning our work and our processes," Stanford was reported as saying. "This could have compounded an otherwise routine examination."