The accounting watchdog said today that the investigation of both Richard Adam and Zafar Khan relates to the preparation and approval of financial statements released by the collapse contractor, namely for the years ended 31 December 2014, 2015 and 2016, and the six months ended 30 June 2017.

The preparation and reporting of other financial information during the period 2014-2017 will also be under scrutiny.

The FRC is already investigating KPMG’s audit of the financial statements of Carillion having launched a separate probe in January.

The Insolvency Service is also investigating the conduct of directors employed at the point at which the outsourcing giant collapsed, but “also of any individuals who were previously directors”, following a request from business secretary Greg Clark.

The FRC said it is liaising with UK’s Official Receiver, the Financial Conduct Authority, the Insolvency Service and The Pensions Regulator to ensure a “joined-up approach” to the investigation of matters arising from the collapse of Carillion.