IRAN'S hardline judiciary has given the government one month to block Whats-App and other popular instant messaging services, as pressure mounts on reformist President Hassan Rouhani to scale back his social and political reforms.

In the severest warning yet to Rouhani's one-year-old administration, chief prosecutor Gholam-Hossein Mohseni-Ejei accused communications minister Mahmoud Vaezi of failing to unplug social networking sites and apps "with immoral and criminal content".

"Despite a three-month grace period to allow you and your colleagues enough time, no effective action has been taken to filter out immoral and un-Islamic offences," Mr Mohseni-Ejei said.

His ultimatum has come after reports of a police investigation into "widespread dissemination of offensive material" against the leader of the 1979 Islamic revolution, Ayatollah Ruhollah Khomeini.