A British tribunal in charge of investigating public abuse of surveillance admitted on Wednesday that the U.K. government’s spy agency illegally retained communications it swept up from Amnesty International, the largest human rights group in the world.

The revelation, disclosed in a curt email, is particularly shocking given that just last week the Investigatory Powers Tribunal issued a determination declaring that Amnesty was not the subject of illegal spying.

Responding to a complaint that Amnesty and nine other human rights organizations sent the tribunal in April, it said only two of the groups —the Egyptian Initiative for Personal Rights and the Legal Resources Centre in South Africa — had been subject to illegal surveillance.

In the email sent to Amnesty late Wednesday, the president of the tribunal said the unlawful retention of communications it previously said had affected the Egyptian group had in fact affected Amnesty.

The full email is reproduced here:

By Post and email Dear Sirs The Tribunal wishes to apologise for and correct an error in its Determination of 22 June 2015. The small number of documents in respect of which the Tribunal made the finding that there had been a breach by virtue of the exceeding of time limits for retention (and which have now been delivered to the Commissioner for safekeeping, insofar as not destroyed) in fact related to Amnesty International Ltd (the 4th Claimant in IPT/13/194/H) and not the Egyptian Initiative for Personal Rights (the 3rd Claimant in IPT/13/168-173/H). This mistaken attribution in our Determination, which has now been drawn to our attention by the Respondents, did not result from any failure by them to make disclosure. Yours sincerely Sir Michael Burton

President of the Investigatory Powers Tribunal

Amnesty International responded with outrage. In a press release, it described the tribunal’s email as a “shocking revelation” that “made no mention of when or why Amnesty International was spied on, or what was done with the information obtained.”

“The revelation that the U.K. government has been spying on Amnesty International highlights the gross inadequacies in the U.K.’s surveillance legislation,” Salil Shetty, Amnesty’s secretary general, said in a statement. “If they hadn’t stored our communications for longer than they were allowed to by internal guidelines, we would never even have known. What’s worse, this would have been considered perfectly lawful.”

Gauri van Gulik, Amnesty International’s deputy director for Europe and Central Asia, marveled at the absurdity of the situation. Amnesty had spent 18 months trying to determine which groups were surveilled, culminating in last week’s ruling, she explained to The Intercept. And now, she said, it turns out there was “a mistake made in the numbering of the complaints.” The mistake was apparently pointed out to the tribunal by GCHQ, she said. “Of course they sat on it for 10 days.”

“Most important to us is that privacy matters. Privacy matters to us. It’s harmed the trust that human rights defenders have in us,” she said. “This has gone too far.”

Naureen Shah, director of security and human rights for Amnesty International USA wrote in an email to The Intercept that her group is concerned that the U.K. “is sharing its collected intelligence from Amnesty with the U.S. government, including communications from U.S. citizens like me and/or communications about our documentation of human rights abuses committed by the U.S. government.”

Amnesty International, founded in 1961, is the largest global human rights groups in the world, and has received a Nobel Peace Prize for its work. The group now joins a large pool of non-governmental organizations targeted by Government Communications Headquarters — or GCHQ, the U.K. equivalent of the National Security Agency in the U.S. Those include Unicef and Médecins du Monde, according to top-secret documents released by The Guardian in December 2013.

Other privacy groups reacted strongly to the revelation. “Today’s farcical developments place into sharp relief the obvious problems with secret tribunals where only one side gets to see, and challenge, the evidence,” Eric King, deputy director of the London-based Privacy International, said in a statement. “Five experienced judges inspected the secret evidence, seemingly didn’t understand it, and wrote a judgment that turned out to be untrue. We need to know why and how this happened.”

He concluded: “Any confidence that our current oversight could keep GCHQ in check has evaporated. Only radical reforms will ensure this never happens again.”

The complaint from the 10 groups said that the collection and inspection of their messages threatened the victims of human rights abuses, lawyers, whistleblowers and others who depend on confidentiality when speaking with them. “The integrity of the Applicants’ communications and the protection of their sources is of paramount importance in order for them to effectively fulfill their role to seek, receive and impart information of public interest,” reads the complaint.

The tribunal notably did not rule that the U.K. spy agency’s initial interception of communications was unlawful, just that retention rules had been violated.

(This post is from our blog: Unofficial Sources.)

Photo of Amnesty International protest in London by Malcolm Park/Getty