(CNN) -- Shahram Amiri -- a nuclear scientist Tehran claimed was kidnapped by U.S. agents -- told a state-run television station in Iran that he was abducted by U.S. intelligence officials and faced "psychological warfare and pressure that are much worse than being in prison."

State-run Press TV said Wednesday that Amiri spoke in an interview after his escape, telling the channel, "I think I will be unable to get into details during this limited period of time and I will postpone it to when I am hopefully in my dear country Iran, so I can speak to the media and my own people with ease of mind and tell them about my ordeal over the past 14 months."

Amiri has left the United States and is headed back to Iran, the country's state-run media said Wednesday morning.

"Following the Islamic Republic's efforts and with the effective cooperation of the embassy of Pakistan in Washington ... Shahram Amiri left the United States and will arrive in Tehran via a third country," the news agency, IRNA, reported -- quoting a foreign ministry spokesman.

Amiri, who is a researcher from Tehran's Malek Ashtar University, mysteriously disappeared in June 2009 while on a religious pilgrimage to Saudi Arabia, according to Iranian media reports.

On Monday, Amiri went to Iran's Interest Section at the Pakistani Embassy in Washington and asked to be sent home.

The Iranian government has accused the United States of involvement in Amiri's disappearance, with Iran saying the researcher was taken to force him to give up data about Tehran's nuclear program.

In the Press TV interview, Amiri said he was kidnapped in Medina, Saudi Arabia, by three men in a van.

"Once I got into the van, the man who was inside said to me, 'Don't make any noise.' I was confused at the moment and had no idea what was happening," Amiri said Wednesday.

According to Amiri, he was later drugged and transported to the United States in a plane.

"I was under very special circumstances for 14 months in the United States. I was not completely free, nor was I like a prisoner, that is, in shackles as viewers might think," Amiri added. "I was in a completely unique situation which is very difficult to describe."

Press TV reported that Amiri was offered $10 million in bribes to cooperate with the United States.

A top Iranian lawmaker recently claimed that newly found documents back up Tehran's claims that the CIA is responsible for Amiri's disappearance, Iranian media reported Sunday.

Javad Jahangirzadeh, a member of Iranian parliament's National Security and Foreign Policy Commission, said Iranian officials had turned over the documents to the Swiss ambassador in Tehran.

The U.S. State Department has denied that charge.

A U.S. official, who is not authorized to talk to the media about such issues, told CNN last month that it would be "ludicrous, absurd and even preposterous" to claim an individual was kidnapped by the United States and held against his will.

Last month, two videos surfaced on the Internet of a man claiming to Amiri, in which he said he had escaped from U.S. agents and was hiding in Virginia.

That was the third time that videos allegedly showing Amiri had been circulated on the Internet.

In one, he said he had been kidnapped by U.S. agents. Another contradicted that claim and said he was living freely and studying in Arizona.

In one of the videos posted June 30 on YouTube and dated June 14, the man again said that he was brought against his will to the United States and fears he will be discovered and re-arrested.

"I am Shahram Amiri, the son of the Islamic Republic of Iran, who with God's help succeeded in running away from the U.S. security agents in the state of Virginia. I am [temporarily] at a safe place and I am trying to do this video but it is quite possible that I may shortly be again arrested by American security agents."

He went on to say: "I am not free here and not allowed to contact my family or other people. If I face any problems or if I do not return to my country soon, the government of the U.S. would be directly responsible for it."

CNN could not independently verify the authenticity of the videos, nor the identity of the man in them.

"If he is who people think he is, the U.S. would be in contact with the person," a CIA official said last month. And if he were being held against his will, "how would he have been able to produce any of the videos?" the official said.

In the second video that surfaced June 30 and dated June 23, the man claiming to be Amiri reassures his family about his well-being.

"I want to let my beloved family know that I am OK and they should not worry about my health," he says. "With God's help I shall return to my beloved country in the next few days. I want them to be, as always, strong and patient and to pray for my safe return. I hope to see you in our beloved country."

Tehran blamed Washington for Amiri's disappearance shortly after revelations surfaced that Iran has been building a second uranium enrichment facility near the city of Qom. After that, tensions over Iran's nuclear program mounted.

Iran claims its nuclear energy is solely for civilian purposes. But the United States has pushed the United Nations to punish Tehran for its nuclear ambitions. The Security Council recently slapped a fourth round of tough sanctions on the Islamic republic.

It is unclear how much information Amiri was privy to in Iran.

CNN's Shirzad Bozorgmehr contributed to this report.