The Afghan authorities announced that they are investigating reports that dozens of Afghan immigrants were tortured by Iranian security forces before they were thrown into the river where two of them died by drowning.
Afghan officials said a campaign had been launched to search for the bodies of dozens of Afghan immigrants in a river in the western province of Herat
But the Iranian side denied these allegations.
Hundreds of Afghans cross into Iran every day in search of work.
According to local media reports, about fifty migrants attempted to enter Iran illegally on Saturday before they were stopped by the border guards who allegedly assaulted the migrants and dumped them in the Harird River that runs between the two countries.
Some managed to escape, but many are still missing.