The US markets watchdog has unsuccessfully attempted to question the London auditor of the bank owned by Allen Stanford, the Texan billionaire caught up in an alleged $8bn (£5.5bn) fraud.

Celia Hewlett, owner of audit firm CAS Hewlett, which has an office in Antigua and was formerly based in north London, may still come under the spotlight of the SEC and the SFO in relation to the Stanford International Bank fraud .The US markets watchdog refused to elaborate its plans, but refused to rule out further efforts to speak to Hewlett in relation to its investigation of Stanford.

On its website, the SEC said: ‘SIB’s accountant, CAS Hewlett & Co, a small accounting firm in Antigua is responsible for auditing the multi-billion dollar SIB’s investment portfolio. The commission attempted several times to contact [CAS] Hewlett by telephone. No one ever answered the phone.’

This week the SEC told Accountr: ‘Absolutely no comment.’

In the UK the Serious Fraud Office said it did not have an investigation into Hewlett or the audit firm under way, but would be ‘monitoring developments closely’. A spokesman said: ‘We are touching base with other authorities to see if there is a possible UK element.’

Last week, The Times quoted Celia Hewlett in Palmers Green, London. An employee at the Antiguan office told Accountr she had not been seen for a fortnight.

Hewlett’s father Charlesworth, founder of the firm, was affiliated with the ACCA, but the institute said she was not a member.

‘Celia Hewlett, is not a member of ACCA. CAS Hewlett & Co has operated under its licence from the Institute of Chartered Accountants of Antigua and Barbuda throughout.’

Nigel Hamilton-Smith and Peter Wastell, two partners at Vantis Business Recovery Services, have been appointed by the Financial Services Regulatory Commission of Antigua and Barbuda as joint receivers of Stanford International Bank Ltd and Stanford Trust Company Ltd.

Along with a team of recovery specialists, they are currently on site in Antigua at St John’s working with the FSRC, management and staff.

Hamilton-Smith said: ‘We are now seeking to establish and protect the position with the investors’ deposits, the companies’ assets and claims from investors.’