The firm announced the decision this morning as it also revealed plans to close the Middle East business after completing the sale of its Far East and India operations.

The cost consultant’s remaining operation is being restructured into five business units covering: London; England and Wales; Scotland and Ireland; Mainland Europe; North America.

A company statement this morning said: “The SFO investigation with respect to Sweett Group into the allegations made in the Wall Street Journal in June 2013 is at an end.

“During the process of our own investigations two related contracts within the Middle East were identified as suspicious and were duly reported to the SFO.

“This has led to an admission by Sweett Group of an offence under Section 7(1) of the UK Bribery Act 2010 – failing to prevent an associated person bribing another to obtain or retain business for the company.

“Subsequent prosecution is expected, with the likely outcome of a fine,” it added

Importantly, the offence does not attract a mandatory ban from public sector tendering under EU/UK law.

Douglas McCormick, chief executive officer, said: “Today’s announcement brings closure on the Middle East legacy issues a step closer, allowing the group to progress unencumbered in the future.

“This is an important next step in the strategic turnaround of the business.”

The separate restructuring of Sweett following the sale of its asia pacifice operation and plans to exit the Middle East have triggered a corporate reshuffle.

Also unveiling first half results the firm reported a £500,000 pre-tax loss, after incurring further £900,000 costs during the period on legal expenses due to the investigation.

Revenue from continuing operations rose £30.2m (H1 2015: £27.8m).