The UK border Agency is trying to deport a gay man back to Tanzania in east Africa where he faces arrest and persecution.
Edson Cosmas came to study in Britain in 2006.
He went to the UK Border Agency offices in Croydon to claim asylum on 9 May this year.
He was seized when he made the application and taken to Harmondsworth detention centre near Heathrow.
On 18 May his supporters say he was given a letter stating that his application had been turned down.
This is despite the fact that he is known in Tanzania to be gay, which is illegal in the country and can carry a 25 year prison sentence. Edson says that he previously faced beatings and threats, and it is not safe for him to return.
The Home Office says that the fact he left it so long before making his claim means it is less credible, as does the fact that his student visa has already expired. Edson says he did not know it was possible to claim asylum for being gay.
The government promised last year that no one would be deported who would be likely to face persecution for their sexuality. Previously it had argued that people could be deported as they could avoid persecution by not being open about their sexuality. Between 2005-2009 almost all gay and lesbian asylum seeker claims were initially refused.
Sign the online petition www.gopetition.com/petitions/free-edson-cosmas-–-gay-tanzanian-activist-detained.html