Yahoo’s top lawyer published an open letter on Wednesday, "demanding" that the Office of the Director of National Intelligence “provide clarity” about whether the company was ordered to perform mass spying on all of its users.

Earlier this month, Reuters reported that Yahoo “complied with a classified US government directive, scanning hundreds of millions of Yahoo Mail accounts at the behest of the National Security Agency or FBI, said two former employees and a third person apprised of the events.” It is not clear what data, if any, was handed over.

If such an order exists, Yahoo would almost certainly be forbidden from discussing it publicly lest it face legal sanctions.

The letter, written by Ron Bell, Yahoo’s general counsel, was addressed to James Clapper, the head of the ODNI. It continues:

Your office, however, is well positioned to clarify this matter of public interest. Accordingly, we urge your office to consider the following actions to provide clarity on the matter: confirm whether an order, as described in these media reports, was issued; (ii) declassify in whole or in part such order, if it exists; and make a sufficiently detailed public and contextual comment to clarify the alleged facts and circumstances. We appreciate the need for confidentiality in certain aspects of investigations involving public safety or national security; however, transparency is critical to ensure accountability and in this context must include disclosing how and under what set of circumstances the US government uses specific legal authorities, including the Foreign Intelligence Surveillance Act, to obtain private information about individuals' online activities or communications. Citizens in a democracy require such information to understand and debate the appropriateness of such authorities and how the government employs them.

Last Friday, dozens of members of the House of Representatives also wrote to Clapper, seeking a briefing on the issue.