Jalal Sharafi, who was freed on Tuesday, said the CIA questioned him about Iran's relations with Iraq and assistance to various Iraqi groups, according to state television.
"Once they heard my response that Iran merely has official relations with the Iraqi government and officials, they intensified tortures and tortured me through different methods days and nights," he said.
Sharafi's comments came a day after 15 British sailors released by Iran said they had been subject to psychological pressure and coercion in captivity. The sailors were captured in the Persian Gulf on March 23 for allegedly entering Iranian waters and released Wednesday.
At the time of his disappearance, Iran alleged Sharafi had been abducted by an Iraqi military unit commanded by American forces — a charge repeated by several Iraqi Shiite lawmakers. U.S. authorities denied any role in his disappearance.
"The United States had nothing to do with Mr. Sharafi's detention and we welcome his return to Iran," said Gordon Johndroe, a White House spokesman who was with President Bush in Texas on Saturday.
"The Iranian propaganda machine has been in overdrive since they paraded the British sailors around on TV. This is just the latest theatrics of a government trying to deflect attention away from its own unacceptable actions," Johndroe added.
A U.S. intelligence official, who spoke on condition of anonymity because of the sensitivity of the issue, said the CIA vehemently denies any role in the capture or release of Sharafi. The official dismissed any claims of torture, saying "the CIA does not conduct or condone torture."
In the report Saturday read by a newscaster, Sharafi, second secretary at the Iranian embassy in Baghdad, said he was kidnapped by agents of an Iraqi organization operating under CIA supervision and was badly tortured.
State television said signs of torture were still visible on Sharafi, who is being treated at an Iranian hospital. Images of Sharafi were not shown.
The television quoted Sharafi as saying he was approached by agents while shopping in Baghdad. The agents allegedly showed him Iraqi Defense Ministry identification papers and were driving U.S. coalition vehicles.
He said they took him to a base near Baghdad airport and interrogated him in both Arabic and English, questioning him mainly about Iran's influence in Iraq and assistance to Iraqi Prime Minister Nouri al-Maliki's government and Iraqi groups. Sharafi did not provide additional details about his captors or their nationalities.
U.S. officials allege that Iran provides money and weapons to Iraqi Shiite militias.
After the initial interrogation, Sharafi said that his captors "softened their behavior and showed leniency to encourage" him to cooperate.
"I explained I was unable to do anything outside my legal responsibilities," Sharafi was quoted as saying. "Later, they released me under pressure from Iraqi government officials. They dropped me near the back of the airport."
Several of the British crew members said Friday that they had been blindfolded, bound, kept in solitary confinement and subjected to psychological pressure during their captivity. They said they were coerced into saying they had been in Iranian waters when they were detained, and one said he believed one of his colleagues had been executed on the second day of the ordeal.
Iran dismissed the crew members' news conference as propaganda — just as Britain had condemned the crew members' frequent appearances on Iranian TV during their captivity.