Egypt's top media regulator has put into effect tighter restrictions that allow the state to block websites and even social media accounts with over 5,000 followers if they're deemed a threat to national security.

The Supreme Media Regulatory Council will also be able to impose stiff penalties of up to 250,000 Egyptian pounds ($14,400), all without having to obtain a court order.

Critics say some of the measures, published in the official gazette late Monday, are stricter than those approved by lawmakers last year.

Prominent Egyptian journalists are calling the measures unconstitutional, saying they grant far-reaching powers to authorities to censor the media, in violation of basic press freedoms.

Mohamed Abdel-Hafiz says he and fellow member of the journalists' union will mount a legal challenge to the new measures.