The deportation of Tamil asylum seekers, due for Thursday, has been halted by the High Court in London.
The landmark ruling means that the deportations of all failed Tamil asylum seekers will have to be reviewed.
A UK Border Agency spokesman told Channel 4 News: "We are disappointed with the outcome of this hearing and we will appeal. The ruling does not represent a blanket ban on returns to Sri Lanka."
The judge, Mr Justice Wilkie, said the situation was "virtually unique", as at the same time as this particular case, an immigration tribunal has been hearing evidence on the situation in Sri Lanka. The results from those deliberations will be used to update Home Office guidance on the risks of returning people to the country, reported Channel 4.
Mr Justice Wilkie said that the guidance on Sri Lanka was being considered "virtually afresh" and it was clear that "the existing country guidance will have to change", meaning that the failed Tamil asylum seekers could not be deported.
"That position is one which this court cannot simply blind itself to," he said.
Keith Best, chief executive of Freedom from Torture, told Channel 4 News: "In the face of such overwhelming evidence, it is a sad indictment of our political masters that it has taken a court to impose the precautions that we have repeatedly called for.
"The UKBA's removals policy for Sri Lankan Tamils remains deeply flawed. Until this is remedied many in need of the UK's protection still live with the risk of forced return to torture."
The Sri Lankan High Commission reacted in predictable fashion to a request for a comment on the result.
"We regret that once again, Channel 4 has asked us to comment pre-facto, even before its programme is aired, and without being told precise details of what is due to be broadcast. Going by your past record it is highly likely to be another spurious piece of theatre.
"In addition, the timing of your release appears to be a continuation of your sinister campaign to attempt to discredit Sri Lanka."
