The protests began on December 28 when shopkeepers in Tehran staged a strike over high prices and economic stagnation, but they have since spread to other places and expanded to include political demands.

The Komala party, an exiled Iraq-based Iranian Kurdish separatist group that Tehran considers a terrorist organisation, announced the strike on Wednesday.

"Seven Kurdish opposition parties have called for a general strike tomorrow Thursday," said Komala central committee member Hassan Rahmanpanah.

"The aim of this call is to demonstrate the unified support of the Kurdish people for the struggle and protests being waged by the Iranian people against the Islamic republic," he told AFP.

Rahmanpanah also accused the Iranian authorities of "brutal and criminal attacks" against demonstrators.