US: Iran should help family of missing American

WASHINGTON, Dec 5 (Reuters) - Iran should give the family of a former FBI agent who went missing while visiting the country nine months ago any information it has about his disappearance, the U.S. State Department said on Wednesday.

The family of Robert Levinson, who vanished while on a business trip to the Gulf island of Kish in Iran in March, plans to visit Tehran later this month to press the Iranian government about his case, the State Department said.

"We urge the Iranian authorities to provide all possible assistance to the Levinson family during their journey," State Department spokesman Tom Casey said in a written statement.

Casey said the Iranian government has told the United States that it has investigated Levinson's case but does not know what happened to him.

The United States broke diplomatic relations with Iran after the 1979 Islamic revolution and it typically deals with the Iranian government through the Swiss Embassy in Tehran.

"Despite numerous requests to the Iranians, we have not received any details on the results of the Iranian investigation," Casey said. "We again call upon Iran to share with the Levinson family and the Swiss Embassy in Tehran all information they have uncovered during their investigations into this case."

Casey said Levinson's wife, Christine, their son, Daniel, and other members of the family planned to make the trip to Tehran. In August, the State Department said it had urged the family to think twice about visiting the country, where four other U.S. citizens have been detained this year.

Levinson, a Florida resident who is not one of the four, went missing while on a visit to the Gulf island of Kish. Some published reports have said Levinson traveled to the region to investigate cigarette smuggling.

U.S. officials have said they believe he is in Iran but have no credible information about his whereabouts.