An FBI poster showing a composite image of retired FBI agent Robert Levinson, right, of how he would look like now after five years in captivity, and an image, center, taken from the video, released by his kidnappers, and a picture before he was kidnapped, left, displayed during a news conference in Washington, on March 6, 2012. The FBI announced a reward of up to $1,000,000 for information leading to the safe location, recovery and return of Levinson, who disappeared from Kish Island, Iran, five years ago on March 9, 2007. For years the U.S. has publicly described him as a private citizen who was traveling on private business. However, an Associated Press investigation reveals that Levinson was working for the CIA. There has been no hint of Levinson's whereabouts since his family received proof-of-life photos and a video in late 2010 and early 2011. (AP Photo/Manuel Balce Ceneta)

WASHINGTON - Sen. John McCain says he is disturbed the Obama administration has not been more forthcoming about an American who disappeared while on a secret intelligence mission to Iran.

McCain said he is confident the U.S. is doing all it can to learn what has happened to Robert Levinson, but he told CNN's "State of the Union" the CIA has not been forthcoming with the Congress about him. Iran's foreign minister, meanwhile, asserted that Levinson is "not incarcerated by the government and I believe the government runs, pretty much, good control of the country."

An Associated Press investigation published last week found that Levinson was working for the CIA — investigating the Iranian government. The U.S. long has publicly described Levinson as a private citizen who travelled to an Iranian island on private business. McCain, R-Ariz., told CNN "the CIA did not tell the truth to the Congress" about Levinson. He said he doesn't "think there's any doubt" about whether Iran knows Levinson's fate.

But Iran's Foreign Minister Javad Zarif, when asked on CBS' "Face the Nation" where Levinson is, replied: "I have no idea."

"If we can trace him and find him, we will certainly discuss" returning him to the United States, he said.

Secretary of State John Kerry dismissed a suggestion by Levinson's family that the U.S. government was not doing enough to find out what happened to Levinson.

"There hasn't been progress in the sense that we don't have him back. But to suggest that we have abandoned him or anybody has abandoned him is simply incorrect ... and not helpful," Kerry told ABC's "This Week."

"The fact is I have personally raised the issue not only at the highest level ... but also through other intermediaries," said Kerry, noting "we have two other Americans that we're deeply concerned about."

Right now, "we're looking for proof of life," Kerry said.

Iran's press counsellor at the United Nations called on Washington to explain Levinson's mission in Iranian territory, after the AP investigation revealed that he had been on an unauthorized assignment for the CIA when he vanished on Iran's Kish Island in March 2007.

U.S. officials have raised the Levinson case with Iran repeatedly over the years. But until the AP investigation was published, it was not widely known that Levinson was hoping to gather information in his role as an independent contract investigator who expected to be compensated by a group of analysts at the CIA.

After he vanished, the CIA at first told lawmakers he had previously done contract work for the agency, but he had no current relationship with the agency and there was no connection to Iran. However, in October 2007, Levinson's lawyer discovered emails in which Levinson told a CIA friend that he was working to develop a source with access to the Iranian government. The emails were turned over to the Senate Intelligence Committee, which touched off an internal CIA investigation.

Three veteran analysts were forced out of the CIA and seven others were disciplined as a result of a breach of agency rules.

The last photos and video of a bearded, emaciated Levinson were released anonymously to his family in 2010 and early 2011. Investigators say his trail has grown cold since then.

News from © The Associated Press, 2013