A judge in Washington this week ruled that it was permissible for U.S. intelligence agencies to withhold documents from London. British lawmakers are investigating the country's alleged involved in so-called extraordinary renditions.
"Refusing disclosure of key information about the alleged participation of U.K. officials in extraordinary rendition runs the risk of promoting impunity for state officials of the U.K. who may have been party to grave human rights violations," Ben Emmerson, U.N. special rapporteur on human rights and counter-terrorism, said in a statement.
In December, Abdel Hakim Belhaj, Libya's military commander who worked with NATO forces during Operation Unified Protector, claimed London played a role in his illegal rendition and torture while he was held in Libya's Abu Salim jail.
He was captured in Thailand in 2006 and transferred to the Libyan prison. There, he says, he was tortured at the hands of Western and Libyan personnel because he was accused of supporting al-Qaida.
"Transparency is key not only to bring to justice those officials who may have participated in crimes of this kind but also in dispelling unjustified suspicions," said Emmerson. "The unjustified maintenance of secrecy, on dubious legal grounds, only delays efforts at establishing the truth."