Moorcroft hopes the mix of young and old can succeed

He said four medals would be a success, and admitted his job is on the line if British athletes under-perform.

Moorcroft, chief executive of UK Athletics, said the team was in a transitional phase.

He also told BBC Five Live the sport was "cleaner now than ever before" despite a series of drug scandals.

Moorcroft is the latest senior athletics figure to issue a sober assessment of Britain's chances at next month's Games.

Report: GB team 'weaker'

UK Athletics performance director Max Jones has conceded the team is weaker than the 2000 Sydney Olympics squad which won six athletics medals.

Former world 110m hurdles champion Colin Jackson has indicated GB sprinters might struggle to even make the 100m final.

And marathon runner Paula Radcliffe is generally considered to be Britain's only realistic gold medal contender in Athens.

Asked how many medals he thought Britain would win, Moorcroft said: "It could be anything from nought to six-seven.

"But realistically, if we get four medals, we will probably have done pretty well, bearing in mind the age and team we've got.

I think there will be less cheats in Athens than in previous Games David Moorcroft

"We've probably got the extremes of athletes getting towards the end of their careers and athletes at the beginning.

"There is an element of transition, but there is a big wealth of talent there, and talent that is capable of competing against the best in the world."

Of Britain's six Sydney medallists, triple jumper Jonathan Edwards has retired and fellow gold medallist Denise Lewis is struggling to be fit for the heptathlon.

Javelin thrower Steve Backley is nearing the end of his career, while Katharine Merry has been sidelined with injury.

Sprinter Darren Campbell and middle-distance runner Kelly Holmes will hope to pick up medals again, but face tough competition.

Moorcroft accepted he could lose his job and it may affect Lottery funding for athletes if the team do badly in Athens.

"Maybe the regime should change. Maybe some personnel change will happen. I think I should be as vulnerable as the athletes to selection," he said.

The former 5,000m world record holder said he was proud of the integrity of British athletes despite sprinter Dwain Chambers serving a two-year ban for a positive drugs test

"I think athletics now is cleaner than it has been for many, many years," he said.

"We are more likely to catch people who cheat than we were before, and the sport has to live with that pain."