PwC has reclaimed the title of world’s largest professional services firm, after rapid expansion of its consulting business powered it to record its fastest rate of revenue growth since the financial crisis.

The 10 percent jump in gross revenues to $35.4bn boosted PwC above Deloitte by revenues. The growth in consulting comes at a time when regulators are again warning about the potential for conflicts of interest as the Big Four auditors continue to expand beyond their core business of audit.

Dennis Nally, who became global chairman of PwC International in 2009 and who will step down next year, said the results showed the firm had the “capabilities and skills that the marketplace is really looking for”.

PwC’s consulting arm, the engine of its growth for the year to June 30, now accounts for more than 30 percent of total revenues after growing 18 percent to $11.2bn during the fiscal year.

Much of the rapid expansion stems from PwC’s acquisition last year of Booz and Co, which it rebranded Strategy &. Consulting revenue had grown 10 percent in the previous financial year.