CAIRO — Egypt is holding the highest number of journalists behind bars since record keeping began, using the pretext of national security to crack down on press freedoms, the Committee to Protect Journalists said on Thursday.

A prison census conducted by the CPJ on June 1 found at least 18 Egyptian journalists were being held in jail for reasons related to their reporting, the most in Egypt since the CPJ began recording data on imprisoned journalists in 1990.

“The threat of imprisonment in Egypt is part of an atmosphere in which authorities pressure media outlets to censor critical voices and issue gag orders on sensitive topics,” the CPJ said in a report published on Thursday.

Khaled al-Balshy, the head of the freedoms committee of Egypt’s press syndicate, said the number of journalists imprisoned was higher, putting it at more than 30.

“We are in the worst climate for journalism in Egypt’s history,” he said.

CPJ said most of the journalists imprisoned are accused by the government of belonging to or being affiliated with the Muslim Brotherhood, which Cairo designates as a terrorist group.

“These numbers are not accurate and this report is not objective,” a government source told Reuters, adding that all imprisoned journalists were facing criminal charges and were not imprisoned for political or free speech reasons.