The US branch of the now-defunct Al Haramain Islamic Foundation claimed federal officials illegally eavesdropped on their telephone calls without court approval required by the administration’s so-called Terrorist Surveillance Program.

At the heart of their lawsuit, tossed by the federal judge on Wednesday, was a top secret call log that the Treasury Department accidentally turned over to Al Haramain’s lawyers, who say it shows government terrorist hunters listened to their phone conversations with foundation officials living in Saudi Arabia.

The government has designated the former Saudi Arabia-based Islamic charity as a terrorist organisation.

US District Court Judge Vaughn Walker barred the foundation from using the top secret document in the case and dismissed the lawsuit. He gave the foundation 30 days to refile its lawsuit with other evidence proving it was a surveillance target.

Al Haramain lawyer Jon Eisenberg told Walker last year that the lawsuit was dead without the use of the call log to prove illegal surveillance.

But public disclosures about the surveillance program in general and about the charity’s role in particular since then could help foundation lawyers prove their case, Eisenberg said after the ruling was issued.