DAVID ROSS, the entrepreneur under investigation by Britain's financial services authority, yesterday admitted breaching stock market rules, but insisted he had not intended to do so.

Mr Ross also said he had offered to resign from all four public companies he has been a director of because of the inadvertent transgression of the rules.

The belated declaration by Mr Ross of how he pledged shares - in Carphone Warehouse, National Express, Big Yellow and Cosalt - as security against his personal loans looked to have prompted similar disclosures elsewhere yesterday.

Mr Ross stepped down from a third public company in four days by resigning from his post of non-executive director at Big Yellow, the storage company. Earlier this week, he relinquished the positions of deputy chairman at Carphone, the mobile phone retailer, and chairman at National Express, the bus and train operator. He said in a statement: "At the start of this week, David Ross offered to resign from the boards of four public companies as a result of an unintentional technical breach of disclosure rules concerning the use of shares he owns in them . . . David is now focused exclusively on managing his private business interests in an orderly manner, particularly through the present period of market turbulence."