The ebbing popularity and tattered image of the 28-year-old chain has convinced the group's chief executive David Thomas that change is needed.

"We've put in place a number of actions to address its performance and improve returns," Mr Thomas said.

"This may mean that a number of sites are converted to other brands while a number of under-performing units may be sold."

Whitbread did not specify how many of its Beefeater restaurants could be at risk.

Tough targets

Whitbread wants the 250 Beefeater restaurants to measure up to its other restaurant, hotel and fitness chains, including Travel Inn, Pizza Hut and David Lloyd Leisure.

Beefeater's sales grew just 1.4% during the six months to August and that is not good enough for the parent which is aiming for growth of 5%.

Last year, Whitbread sold its pubs and bars because it believed that business prospects were greater in the leisure industry.

The group also recently sold its Cafe Rouge and Bella Pasta chains because they failed to meet financial targets.

Pub performance?

The question now is whether Beefeater's performance is more like that seen in the pub sector.

"The top Beefeater sites average £23,000 a week and an 18% return on capital.

"So the potential is there," said Mr Thomas.

"It would be crazy not to try and get the best out the chain before more radical action is contemplated," he added.

Strong profits

Overall, Whitbread's pre-tax profits rose 11% during the first half of this year to £121.3m ($189.1m) before one-off expenses.

"These results provide further evidence of the benefits from transforming Whitbread into a focused company with strong brands, high quality assets and first rate people," said Mr Thomas.

By 0920 GMT Whitbread shares were up 6.6% at 533 pence.