According to The Times, after weeks of tension and counter-claims on both sides, the Accounting & Actuarial Discipline Board will open an inquiry within weeks and look into the work provided by PwC.
Earlier this month lawyers reportedly told Tenon they may have the basis for a legal claim after having “serious concerns” about the quality of the accountancy giant’s audit.
The firm claims mistakes made by PwC contributed to the collapse of buyout talks by private equity firm HG Capital.
PwC responded by accusing Tenon of misleading its audit team "through both omission and deliberate misrepresentation."
RSM Tenon has had a tumultuous few months, after revealing in January its chief executive Andy Raynor and chairman Bob Morton had stepped down amid mounting losses.
In February Tenon revealed an £84m first-half loss after taking a £61m writedown of goodwill, and admitted to "significant errors" in its last full-year accounts.