The disciplinary body said the investigation would focus specifically on the group’s results for the year to August 31 2009 and the six months to February 28 2010.

Investigators are expected to look closely at mobilisation costs. Most contractors recognise the upfront costs immediately in their profit and loss accounts, while others spread them out over the lifetime of the contract.

Connaught was rumoured to have a more aggressive accounting method for dealing with the costs.

Connaught’s auditor PricewaterhouseCoopers said in a statement that it would co-operate fully with the AADB investigation.

The inquiry will also focus on the conduct of other members of the Institute of Chartered Accountants in England and Wales.