Iran hosts the second largest number of Aghan refugees in the world after Pakistan, with about 1.4 million documented immigrants, including almost 830,000 refugees who fled conflict at home.

Many of the immigrants have no option other than engaging in labour work, including construction jobs, to survive and support their families back home.

Despite living in the country for years, a significant number of Afghans complain of discrimination by their hosts, saying they have been denied refugee status and given temporary work visas.

The Iranian government has already forced many to return to Afghanistan.

However, representatives of the UN in Iran have said that it is unfair to criticise Tehran because it is treating the refugees better than most countries have.

Speaking to Al Jazeera, Bernard Doyle of the UN refugee agency in Iran, said: "Iran is an example.

"It does a lot of work in the country also the level of education Iran provides to them here is invaluable, it means this country is providing a very high level of education to Afghani people."

Al Jazeera's Soraya Lennie reports from Tehran.