By Dominic Casciani
Mr Mohamed: Protracted legal battle deepens
Senior judges say the foreign secretary is stopping them releasing details of CIA interrogation techniques - even though the US has published them.
The High Court says it wants to refer to previously classified documents as part of its judgement on the alleged mistreatment of Binyam Mohamed.
Mr Mohamed says the US tortured him after his arrest in Pakistan in 2002.
The declassified material is online - but the UK says using some of it in court would harm national security.
Mr Mohamed, an Ethiopian national, says he was tortured at the behest of the US in Pakistan, before being subjected to further ill treatment in Morocco. He was eventually taken to Guantanamo Bay in Cuba but released to return to the UK earlier this year.
In October, the High Court said it wanted to release a seven-paragraph summary of Mr Mohamed's alleged treatment. That summary is based on CIA material passed to British security officials.
Foreign Secretary David Milliband says publication of that summary would damage national security because the US would stop sharing information. The government has also stopped the judges from publishing the full reasoning for their decision.
But on Thursday, Lord Justice Thomas and Mr Justice Lloyd Jones hit back, saying the censored passages were in fact partly based on legal papers that US President Barack Obama had voluntarily declassified in April.
Some of the documents that are now publicly available cover the interrogation techniques used on a high-ranking al-Qaeda prisoner, Abu Zubayah.
These techniques include waterboarding, sleep deprivation and putting detainees in confined spaces with insects.
Reprieve, the legal charity backing Mr Mohamed's case, said Mr Miliband was using an "Alice in Wonderland" argument to claim the documents were not public.
"It is truly bizarre that much of the information that the foreign secretary is seeking to redact from these judgements is already in the public domain," said Claire Algar, director of Reprieve.
"The government's obsession with secrecy is starting to feel like a hall of mirrors. Nobody believes that disclosure will upset the US when the very same information has already been disclosed by the Obama administration."
But a Foreign Office spokesman said there would be an urgent appeal - and warned that intelligence-sharing with the US was at risk.
"We are appealing the court's recent judgments in the strongest possible terms, and will argue our case before the Court of Appeal," said the spokesman.
"We are objecting to publication of a small number of paragraphs
on the basis that they indicate the content of the seven paragraphs at issue in the case - and therefore publication would cause harm to our national security."
"We have repeatedly made clear that it is not for the UK to release US intelligence. The issues at stake go to the heart of the UK's intelligence-sharing relationship with other countries and our efforts to defend UK security."