Abd al-Rahim al-Nashiri, a detainee at Guantánamo Bay and accused mastermind behind an al-Qaida bombing, has lodged a complaint against UK intelligence agencies MI5, MI6, and GCHQ, alleging their complicity in his torture and mistreatment by the CIA.

Lawyers for al-Nashiri, who was first detained in 2002 under the CIA’s post-9/11 secret detention and interrogation program, argued in UK’s Investigatory Powers Tribunal (IPT) that the UK intelligence agencies were indirectly involved in his abuse. Despite the grave allegations, the UK government asserts that the IPT lacks jurisdiction to consider al-Nashiri’s case.

Al-Nashiri’s legal counsel has submitted documents to the tribunal, stating, “The complainant’s case is that the UK agencies aided, abetted, encouraged, facilitated and/or conspired with the US authorities in his mistreatment.” After his capture, al-Nashiri was placed in the CIA’s network of clandestine prisons known as black sites. A US Senate investigation later found that he was severely tortured during his four-year detainment, including waterboarding, mock executions, and rectal feeding.

In 2006, following his prolonged stay at the CIA facilities, al-Nashiri was transferred to Guantánamo Bay in Cuba, where he has been held since. His complaint to the IPT alleges that he was of “specific interest” to British intelligence during the 2000s and possibly among the group of detainees the UK allegedly had a hand in torturing. The complaint also suggests that the UK’s role in al-Nashiri’s mistreatment could have extended to permitting Luton airport to refuel a private jet used in his rendition from Thailand to Poland in 2002.

If the IPT agrees to hear al-Nashiri’s case, it could reopen the debate on the UK’s alleged involvement in the CIA’s detention program. A 2018 parliamentary intelligence and security committee report concluded that UK spy agencies played a part in the CIA’s kidnapping and torture of terrorism suspects. However, the committee stated that their inquiry was “terminated prematurely” due to government obstruction, leaving several questions unanswered.

Currently awaiting trial for the USS Cole bombing in a military tribunal at Guantánamo Bay, al-Nashiri’s case has been under intense scrutiny by the European Court of human rights. The court ruled that Poland, Romania, and Lithuania violated human rights while aiding the CIA’s black sites operation. The UK government has yet to confirm or deny the allegations related to al-Nashiri’s case, maintaining a policy of silence on the activities of its intelligence agencies.