The accounting probe is being carried out by Isoft's auditors, Deloitte, and will be complete within weeks, according to Isoft spokesman John White.

The company has stated that the investigation will not have a material impact on its revenue or profit figures for 2006 but that it might lead to results reported in previous years being restated.

The investigation is the latest in a series of setbacks for Isoft. Delays in implementing the British government's National Programme for IT caused it to issue a profit warning earlier this year. The company has since entered negotiations with its bankers and with creditors to reschedule payments and give it some breathing room and it recently announced it would have to delay the announcement of its quarterly results to the London Stock Exchange, due last month, until it reaches agreement.

"I would hope we're in a position to bring these things together and announce our results by the end of the month, " said White.

Isoft has received 10.8m from the HSE to date. A HSE spokeswoman said further payments would be made only when various milestones set out in the fixed price contract were completed.

White said Isoft had assured its customers that the company would remain solvent and would fulfil all its contractual obligations.