"I was arrested at work and confined for two nights in a dark cell," Mohammadi told IRIN on Sunday in the Afghan border district of Islam Qala where deportees from Iran were taken.
"I have no news of my family, and my wife and children don't know where I am either," said the father of two who did not have a work permit for his job as a foreman in Tehran.
The Iranian government has recently stepped up efforts to expel Afghan labour migrants and numerous other Afghans who reside in Iran without formal permits.
"After consultation with the Afghanistan government and the UN, we have decided to deport all illegal Afghan workers and emigrants from Iran," said Mohsin Hashimi, an official at the Embassy of Iran in the Afghan capital, Kabul.
Afghan Foreign Ministry spokesman Sultan Ahmad Baheen said about 30,000 Afghan refugees, including women and children, had been sent home from Iran in the past week alone, Reuters reported.
Afghan officials have called on their Iranian counterparts to adopt a gradual approach in the deportation of illegal Afghan migrants in Iran. "It is impossible for us to integrate thousands of deported young men in Afghanistan over a short period of time," Shojauddin Shoja, an adviser to Afghanistan's Ministry of Refugee Affairs, said.
It is unclear how many Afghans live and work in Iran without formal documentation. Iran says around one million Afghans living there have illegally entered and will be sent home. However, some 900,000 Afghans have refugee identity cards, which legalise their stay in the host country.
Unregistered Afghans in neighbouring Iran and Pakistan do not have refugee status and thus do not qualify for UNHCR's legal and humanitarian assistance, the UN refugee body said.
"Only the 900,000 Afghans who have refugee identity cards in Iran are our concern. Those who live or work illegally are not eligible for UNHCR's protection and assistance," said Abdul Basir Mohmand, a UNHCR official in the western Afghan province of Herat.
The UN refugee agency has urged the governments of Iran and Afghanistan to find a viable mechanism to solve the problem of Afghans informally working and living in Iran.
Many deportees accuse Iranian security police of ill-treatment.
"During my 48-hour detention I was given no food," said a young Afghan deportee who accused the Iranian police of having robbed him.
Another deported man showed his stained shirt and said, "they [Iranian security forces] kept on punching and kicking me in the face and head while I was bleeding".
However, an Iranian diplomat in Kabul denied all charges of wrongdoing by his country's security forces. "Afghan media have exaggerated the reports of disputes between Iranian police and illegal refugees," said Hashimi of the Iranian embassy in Kabul.
Facing various socio-economic problems, Afghan workers, for decades, have searched for employment opportunities in neighbouring countries, primarily Iran and Pakistan.
Cheap and hard-working Afghan workers are often hired in these two countries without a formal contractual agreement, analysts and aid workers say.
However, the simple economics of the earnings gap is likely to continue to fuel labour migration from Afghanistan, analysts say. An unskilled Afghan worker can earn US $1-3 per day in Afghanistan, but can get $7-9 per day in Iran, according to a 2005 research study by the Afghanistan Research and Evaluation Unit (AREU), a local think-tank.
"I will get a passport and an Iranian visa and will go back to Iran for work," a deported Afghan said.