Speculation about a bid for M&B began in March

M&B, owner of the Harvester and All Bar One chains, had already rejected the approach and refused to discuss a deal.

The R20 consortium led by tycoon Robert Tchenguiz said it reserved the right to return with another offer in the next six months if the situation changed.

It had proposed merging M&B's pub chain with Mr Tchenguiz's Laurel Pub Company.

M&B, which operates about 2,000 outlets across the UK, emerged as a potential bid target for Mr Tchenguiz in March, and the Takeover Panel had given him until 8 May to make a formal bid or walk away.

M&B CHAINS All Bar One Toby Carvery O'Neill's Vintage Inns Ember Inns Sizzling Pub Co Edward's Scream Harvester Browns See M&B's share price

M&B had set out a robust defence to the approach, saying that its like-for-like sales - a measure which strips out the impact of new outlets - had grown at the fastest rate in the sector over the past two years.

In April it said it would seek to return at least �500m to shareholders this year if it could not find any suitable takeover targets itself.

M&B welcomed the news of R20's withdrawal, and said: "The board believes that the company has excellent prospects for organic growth and is well placed to take advantage of consolidation opportunities."