The head of Egypt's journalists union says he has notified the country's top prosecutor that 10 journalists have gone on hunger strike against a restrictive protest law imposed last year.

Diaa Rashwan said Saturday that he sent an official notification to Hisham Barakat about the hunger strike, which will take place in the syndicate's headquarters in downtown Cairo.

Dozens of prisoners have been joining an ongoing hunger strike against the contested law, which bans demonstrations without a permit and toughens penalties on violators.

Tens of thousands of people, mainly supporters of ousted Islamist President Mohammed Morsi, were detained after his overthrow last summer. Some have been charged under the protest law.