The team behind Facebook are having a pretty tough time of it at the moment.

First there was outrage at one of the SuperPoke applications, then Facebookers in the US and Canada had to watch as their beloved Scrabulous was removed, and now the social networking website has come under fire for one of its ads.

The advert in question is for a slimming patch called Pink Patch, which claims to be able to help you lose a stone (6.35kg) in 2 weeks.

The Advertising Standards Agency has now banned the ad from Facebook after branding it "irresponsible" and claiming it promotes "bad medical practice".

The ASA said there was no evidence that the herbal ingredients in the patch caused any loss of weight.

The ASA judgement said: "The evidence did not persuade us that wearing the Pink Patch would result in a loss of body fat and we concluded that the claim 'drop a stone in two weeks' was unsubstantiated and could mislead".

ASA spokeswoman Olivia Campbell added to the BBC: "The ad was irresponsible for promoting bad medical practice of losing a stone in two weeks and failed to provide persuasive scientific evidence to substantiate its claims".

The company behind the advert, CYC Marketing, is not commenting.