By Pam O'Toole
BBC regional analyst
The United Nations refugee chief says thousands of Afghans may have been forced to return to Afghanistan because of Iran's policies.
There are more than a million Afghan refugees in Iran
The UN High Commissioner for Refugees has been increasingly concerned that Iranian officials are pressurizing Afghan refugees to go home.
There have been radio campaigns informing them that they have to leave.
Rudd Lubbers told the BBC that such actions went too far, saying thousands may have been forcibly returned.
He said that the UN refugee agency did not want its agreement on voluntary repatriation to be interpreted as being instrumental in deportation.
There have been reports of round-ups, or of people being denied extensions of their residence documents and then being denied access to public services, or even being arrested, for having no documents.
The high commissioner, who has just returned from a visit to the region, said there were indications that some Afghan refugees as well as illegal Afghan migrants, were being pushed out of Iran.
He said the UNHCR wanted more intensive discussions with Tehran before extending their current voluntary repatriation agreement.
"When we had a return last year of 380,000 [people from Iran] certainly not all was forced, no. The large majority was voluntary," he told the BBC.
"But when there are, let's say, 5% of them forced, it's 5% too much - we are talking almost 20,000 people. Therefore, I confirm that we are talking of a problem of at least thousands if not ten of thousands," he added.
Tehran has denied forcing legitimate Afghan refugees home, but says it has arrested many illegal Afghan workers.
Mr Lubbers said voluntary repatriation to Afghanistan should continue at the current rate for some time.
But he added that in the long-term, it would be useful if Iran, Pakistan and European countries hosting Afghans would also consider allowing some to remain as migrant workers.
The UNHCR, he said, was arranging a conference with European countries, Iran, Pakistan and Afghanistan next month to discuss this and other long-term solutions for Afghan refugees.