KABUL: Afghans fleeing fighting at home and seeking refuge in neighbouring Iran face increasing persecution by the Iranian government, Human Rights Watch said in a report on Wednesday.

The report, “Unwelcome Guests”, details a growth in arbitrary arrests, detentions, beatings and harassment of more than a million Afghans as Iran faces its own economic problems worsened by international sanctions.

The New York-based rights group cited unidentified Afghan officials accusing Iran of using deportations as a form of political blackmail against the Afghan state, which already struggles to provide for citizens living within its borders.

“In recent years conditions have worsened and pressures increased for nearly all Afghans in Iran,” the rights group said.

“They face higher barriers to humanitarian aid and social services, arbitrary arrest and detention, and have little recourse when abused by government or private actors.”

Officials at Iran's embassy in Kabul could not be reached for comment.

Afghan refugees in Iran have for many years enjoyed relatively good living conditions and opportunities.

But sanctions imposed over Iran's nuclear program have led to significant inflation and unemployment that have hampered Tehran's ability to care for its most vulnerable inhabitants, Human Rights Watch said.

The report was released on the eve of the latest round of talks in Geneva between Iran and the United States, Russia, China, France, Britain and Germany.

The talks are aimed at clinching a deal on the scope of Iran's nuclear work in return for sanctions relief.

Decades of war, oppression and banditry have driven millions of Afghans to seek better lives in other countries, mainly across the border in Pakistan and Iran.

Just over 840,000 of the 2.4 million Afghans living in Iran are registered as refugees, Iran's immigration bureau says.