Rights groups expressed alarm on Saturday that Iranian authorities were intensifying a deadly crackdown under cover of an internet blackout, after another night of mass protests in the biggest demonstrations to face the Islamic Republic in years.The two weeks of demonstrations have posed one of the biggest challenges to the theocratic authorities who have ruled Iran since the 1979 Islamic revolution, although supreme leader Ali Khamenei has expressed defiance and blamed the United States.For all the latest headlines, follow our Google News channel online or via the app.Following the movement’s largest protests yet on Thursday, new demonstrations took place late Friday, according to images verified by AFP and other videos published on social media.This was despite an internet shutdown imposed by the authorities, with monitor Netblocks saying Saturday evening that “Iran has now been offline for 48 hours.”Amnesty International said it was analysing “distressing reports that security