PARIS: Rights groups accused Iranian security forces of shooting at demonstrators as the death toll mounted on Thursday from a crackdown on economic protests and a watchdog reported an Internet blackout across the Islamic republic.

Twelve days of protests have troubled the clerical authorities under Ayatollah Ali Khamenei already battling an economic crisis after years of sanctions and recovering from the June war against Israel.

US President Donald Trump meanwhile threatened on Thursday to take severe action against Iran if its authorities “start killing people,” warning Washington would “hit them very hard.”

The movement, which originated with a shutdown on the Tehran bazaar on December 28 after the rial plunged to record lows, has spread nationwide and is now being marked by larger-scale demonstrations.

Videos on social media showed that protests were again taking place Thursday.