India, Jan. 2 -- Iran has been rocked by its biggest protest in three years against economic stagnation and high inflation, with clashes erupting between security forces and demonstrators as rallies spread to other cities across the country, including the clerical stronghold of Qom.

The protests in Iran prompted US President Donald Trump to issue a warning to the Iranian government of coming to the "rescue" of "peaceful protesters" if they are shot at or "violently killed".

The protests began on Sunday after shopkeepers took to the streets over the government's handling of a sharp fall in the currency and rising prices. Merchants, shop owners and students at several Iranian universities have been protesting for days and shutting down ma...