A Facebook group that encourages social network users to post photographs of women on public transport has been accused of breaching women's civil liberties.
The group, Women Who Eat On Tubes, asks its 14,000 members to post photos that "celebrate" women.
A statement on the page, which has more than 14,000 members, says: "We celebrate and encourage women eating food on tubes, we do not marginalise them. We always look for the story in the picture. We don't swear. Subjects are embraced and cherished."
The page said it is "observational not judgemental" adding that it "doesn't intimidate or bully".
But women whose photographs have been posted say they were subjected to abuse by users when they asked for their pictures to be taken down.
But Transport for London said that – while it is not illegal to take photographs of strangers on public transport – any women who feel threatened or believed "there was a sinister motive" should contact British Transport Police to report the photos.
Steve Burton, TfL's Director of Enforcement and On-Street Operations, said: "Taking photos on the Tube isn't illegal, but we ask anyone doing so to ensure that they use common sense and respect for other passengers.
"If someone doesn't want their photo taken it is obviously inappropriate to do so. If any customer has concerns about such behaviour, believing there may be a sinister motive, they are advised to speak to our staff or the British Transport Police."
Privacy campaigners said the law did not protect people if their photographs were taken by strangers on public transport. Anyone who requests it should have the right to demand their photos are taken down from social networking sites and blogs, they added.
Deputy Director Emma Carr, said: "It's obviously not realistic to expect social networks to police whether photographs have been taken with consent, but there is clearly a need to look at where people are creating forums to encourage and share photos taken.
"Equally banning camera phones isn't going to work, so we need to make sure that the law deters people taking photos of other people, especially if their intent is to publish them.
"The laws protecting our privacy were written long before social media, camera phones and widespread broadband access. Cases like this should be dealt with proportionately, and people absolutely need to be able to seek redress if they do not wish to have their photograph on this kind of website. Unfortunately this is a problem that will get worse before it gets dealt with."