An Iranian militant group has claimed to have blown up an oil pipeline in the southern Khuzestan province, the scene of other attacks by Arab separatists.

An online video posted by Ansar al-Furqan claimed the attack and showed what it described as a pipeline near Omidiyeh.

The US-based SITE Intelligence Group quoted the video on Saturday as saying "this operation was conducted to inflict losses on the economy of criminal Iranian regime".

SITE says the attack by Ansar al-Furqan, if confirmed, would be their first in oil-rich southern Iran.

Iran has faced low-level separatist unrest from Kurds in its northwest, the Baluch in its east and Arabs in its south since the 1979 Islamic Revolution.

Iranian authorities have not acknowledged any such attack.

The claim comes as Iran experiences widespread protests as Iranians began to vocalise their discontent toward the ruling regime.

Anti-government protests in Iran entered their third day on Saturday as the regime warned against further "illegal gatherings".

Thousands of Iranians took to the streets in anti-government rallies on Friday, in what is thought to be the biggest show of public defiance since 2009.

The protests came a day after demonstrations against rising food prices and inflation began in second city Mashhad, with authorities arresting 52 protesters over the unrest.