Some of the evidence against Mayor Eric Adams in his corruption case involves classified material that could endanger national security if disclosed, prosecutors wrote in a new letter to a judge.

Assistant Manhattan U.S. Attorney Celia Cohen did not reveal details of the evidence in her request Thursday for an ex parte hearing — without Adams or his attorneys present — before Judge Dale Ho. But the filing, which invokes court special procedures regarding classified information, is a sign that Adams’ bribery case could involve evidence gathered through surveillance of foreigners, according to Sabrina Shroff, a defense attorney with experience trying terrorism and spying cases.

“[The evidence] could belong to Turkey and the United States doesn’t want them to find out how they’re spying on Turkey,” Shroff said.

“It could be that they’re spying on someone and don’t want to disclose that.”

She cautioned that the government tends to over-classify material, and that the evidence in the Adams case could be relatively insignificant. The evidence could have been collected by an array of government agencies, including the CIA, FBI, NSA or State Department, she added.

Adams is charged with five counts, including wire fraud, conspiracy, bribery and soliciting campaign donations from foreigners. The indictment cites text messages involving unnamed Turkish government officials and businessmen who showered Adams with more than $100,000 in travel perks, according to prosecutors.

In one text exchange cited in the indictment, a person identified only as a Turkish promoter hints that high levels of the Turkish government were aware that Adams was elected mayor in 2021.

“I’m going to go and talk to our elders in Ankara about how we can turn this into an advantage for our country’s lobby,” the promoter texted, according to the indictment.