Campaigners are planning to protest outside a Swindon police station where an Afghan teenager is awaiting deportation.
Mohammed Pardesi, 18, who has lived in Swindon for two years, said he fled Afghanistan when his brother was killed by the Taliban.
He has lost his appeal to stay in the UK and was arrested earlier.
The UK Border Agency said a judge had found Mr Pardesi "embellished" his claim for protection.
Mr Pardesi's girlfriend, Emma Williams, has said she will move to Afghanistan with him if he is deported.
Paulette North, who is organising the campaign to keep Mr Pardesi in the UK, said supporters intended to protest outside Gablecross Police Station later.
She said Mr Pardesi firmly believed he would be killed if he returned to Afghanistan.
A spokesman for the UK Border Agency said: "All cases are carefully considered and the UK Border Agency will offer protection to anyone found by us - or the courts - to be at risk.
"Mr Pardesi's claim was turned down by both the UK Border Agency and by the Immigration Tribunal where a judge found he had embellished his claim for protection in the UK in an attempt to give it greater weight.
"We would rather individuals like Mr Pardesi leave the UK voluntarily when they have no basis to remain here, but if individuals defy the decisions of the courts we are left with no choice but to detain them and enforce their removal."
The spokesman quoted Immigration Judge Harmston as saying: "It is just idle speculation on his part to suggest that he would be at real risk of being targeted by the Taliban in Kabul, particularly in the light of my finding that his claim that his paternal uncle had a friend who was 'a very high ranking Taliban member' is untrue.
"It is true that there is indiscriminate violence in the form of suicide bombings even in Kabul, but that indiscriminate risk is not one which gives rise to an entitlement of asylum."