The US-based advocacy group Human Rights Watch (HRW) has accused Iran of violating its legal obligations towards refugees from Afghanistan and failing to protect them from abuse.

In a report published on Wednesday, HRW says thousands of Afghans have been summarily deported from Iran without a hearing of their right to remain.

In its report, HRW says Iranian officials "have in recent years limited legal avenues for Afghans to claim refugee or other immigration status in Iran, even as conditions in Afghanistan have deteriorated".

HRW added that it had evidence of violations including physical abuse, detention in unsanitary and inhumane conditions, forced labour and separation of families.

Last year the Iranian government passed a law that restricts residence permits to those Afghan immigrants who live in three of Iran's 31 provinces.

In November, it ordered 300,000 Afghans living in the country on temporary permits to leave.

According to the Human Rights Watch,  the Iranian government's policies meant many undocumented Afghan children could not go to school, and migrants recognised as refugees were limited to "dangerous and poorly paid" manual labour jobs.

And the group warned of rising anti-foreigner sentiment in Iran which was leaving the Afghan population at risk of physical violence.