Back in August 2013, one of the myriad documents provided by former NSA contractor Edward Snowden showed that several major telecommunications companies provided British intelligence with direct access to their undersea fiber-optic cables.

Now, Privacy International wants answers as to how the Government Communications Headquarters (GCHQ), the British equivalent of the NSA, got its hands on all that data. And as of Monday, Privacy International hopes to use a “non-adversarial arena” as part of the Organization for Economic Co-operation and Development (OECD) to compel answers from one of those firms, Level 3.

Earlier this summer, Privacy International sued the UK government over the surveillance for alleged violations of British law. And now it's filed a new, 25-page formal complaint to the United Kingdom’s National Contact Point for the OECD. Among other things, Privacy International wants Level 3 to “explain all steps taken to oppose, resist, or challenge requests or directions to facilitate GCHQ’s mass interception programs, to the extent that the companies are being legally compelled to cooperate with GCHQ” and to “exhaust all legal avenues available to challenge GCHQ’s requests or directions to facilitate GCHQ’s mass interception programs, to the extent that the companies are being legally compelled to cooperate with GCHQ.”

Level 3 did not immediately respond to Ars’ request for comment.

“With each passing day, the public finds out more and more how private companies are colluding with governments to operate mass surveillance programs that intercept our daily phone calls, text messages, e-mails, and personal data,” said Eric King of Privacy International in a statement.

“It is unconscionable to think that the companies that carry our most personal information either refuse to stand up for us or remain silent when our rights are violated. Far from being coerced, it appears some of the companies have gone well beyond their legal responsibility by colluding with GCHQ on its Tempora program. We call on these companies to do the right thing and halt their involvement with mass surveillance and hope the OECD will investigate what steps, if any, the companies took to defend the human rights of their customers.”