Luke Johnson in PizzaExpress bid

Luke Johnson, the stock market entrepreneur who made his fortune from PizzaExpress, is understood to be working on a bid for the restaurant chain in a move that would see him go head to head with his former business partner Hugh Osmond.

The two entrepreneurs were students together at Oxford University and made £26m from floating PizzaExpress in 1993, but the pair fell out over the bid battle for Whitbread's pubs division.

Mr Osmond emerged as a bidder for PizzaExpress two weeks ago. The company has been losing out to competition from rival high street chains and its falling share price has left it vulnerable to a takeover approach, but the board is expected to reject Mr Osmond's £250m offer. A spokeswoman for PizzaExpress said the company was not aware of an approach from Mr Johnson and no other formal approaches had been made to the group.

"We will put out a formal statement if we receive any approaches," she said. "At the moment we are still dealing with Mr Osmond." Mr Johnson is understood to be working with Hawkpoint Partners, a firm specialising in mergers and acquisitions.

The likelihood of Mr Johnson launching a rival bid for PizzaExpress has been seen as remote by many in the City, on the grounds he is too busy organising a management buyout of his Signature Restaurants business. It is understood, however, that the Signature deal is near completion, leaving Mr Johnson free to pursue other deals.

Contacted in France yesterday Mr Johnson declined to comment.