Shares in Patisserie Valerie have been suspended after the cafe chain discovered “significant, potentially fraudulent, accounting irregularities”.
The company said these could cause a “potential material” mis-statement in its accounts.
Entrepreneur Luke Johnson owns a 37% stake in the businesses, which also includes Druckers, Philpotts, Baker & Spice and the Flour Power City Bakery.
Finance Director Chris Mash has been suspended, the company said.
Mr Johnson said: “We are all deeply concerned about this news and the potential impact on the business. We are determined to understand the full details of what has happened and will communicate these to investors and stakeholders as soon as possible.”
The company, which was listed on the stock market in 2014, said that the board of directors had been notified of the potential irregularities on Tuesday.
It said it had asked for its shares to be suspended while a full investigation was conducted.
The company’s cash position could be affected and “this may lead to a material change in its overall financial position”, it added.