Afghanistan is investigating reports that Afghan migrants drowned after being tortured and pushed into a river by Iranian border guards.
Migrants were caught trying to enter Iran illegally from Herat province on Friday, according to local media.
Migrants were beaten and forced to jump into a river by Iranian border guards, according to reports. Some of them are said to have died.
Iran rejected the claim.
A spokesman for the Foreign Ministry said the incident occurred on Afghan territory, not Iran, and security guards denied any involvement.
The number involved in the incident is not confirmed, but officials said dozens of migrants had crossed the border and at least seven people died with more missing.
A search team was sent to retrieve the bodies of migrants from the river.
- Seven million Afghan children risk hunger
- & # 39; Infected employees & # 39; in the Afghan presidential palace
The Afghan Human Rights Commission (AHRC) said local officials said "Iranian security forces arrested several Afghan migrants in search of work who wanted to enter Iran".
"They were made to cross the Harirud River [at the Afghan-Iranian border]as a result, some of them drowned and some survived, "he added.
Shir Agha, a migrant who witnessed the incident, told Reuters that Iranian guards "warned us that if we don't jump into the water, we will be shot".
Another Afghan migrant, Shah Wali, claimed that Iranian guards "beat us and then made us work hard".
"They then picked us up by minibus near the river and, when we got there, threw us into the river," he added.
About three million Afghans live in Iran, including refugees and wage earners. Hundreds of Afghans cross Iran every day to find work.
There has been a mass exodus of migrants returning to Afghanistan after the coronavirus outbreak in Iran, which has recorded almost 100,000 cases of the disease to date. Many are suspected of bringing the coronavirus back to the border with them.
But as Iran seeks to ease restrictions, Afghan migrants in search of work are crossing the country's border in greater numbers again.
Afghan officials have expressed concern over the incident in Herat province, risking a diplomatic dispute at a time of already strained relations over the coronavirus pandemic.
In a tweet to the Iranian authorities, Herat's governor Sayed Wahid Qatali wrote: "Our people are not just a name you threw into the river. One day, we will settle the score."