US says Iran response on Levinson not credible

WASHINGTON, June 8 (Reuters) The United States cast doubt today on Tehran's claim it still has no information on a former FBI agent who went missing while on a trip to Iran in March and urged its foe to continue pursuing the case.

State Department spokesman Tom Casey said Iran sent another written response on Wednesday to US inquiries over Bob Levinson, a Florida resident and ex-FBI agent not heard from since he visited the Gulf island of Kish three months ago.

''They once again claim to have no information about him. That is unfortunate and we believe that there are many possible leads out there for them to pursue,'' Casey told reporters.

''We just don't think that this is very credible,'' he added.

''We will continue to push this issue with the Iranian government.'' Since mid-March, there have been a handful of diplomatic exchanges about Levinson between Washington and Tehran via the Swiss embassy in Iran. The United States has no diplomatic relations with Tehran and Switzerland acts as a go-between.

''We again know that Mr Levinson did arrive in Iran and we have no information to indicate that he left and that leads us to believe that he is still there and the Iranian government ought to be able to find out something,'' said Casey.

While Iran's government says it does not know anything about Levinson, it has confirmed it is holding four Iranian-American citizens on security-related accusations.

Casey dismissed the allegations against the four and reiterated a demand they be freed immediately and allowed to return to their families in the United States.

''Regardless of the differences between the governments of our two countries, on a basic, human level no one should be faced with imprisonment or fear of harassment simply because they want to try and see their families,'' Casey said.

The two countries are at loggerheads over Iran's nuclear program and refusal to give up sensitive enrichment work that Washington says is aimed at building an atomic bomb and Tehran says is for peaceful power-generation purposes.

The United States also accuses Tehran of meddling in the Iraq conflict. US forces have been holding five Iranians in Iraq since January.

The Bush administration has said the cases of the five detained Iranians and the Iranian-Americans being held by Tehran are separate issues.

Washington cut ties with Iran in April 1980, five months after Iranian students occupied the U.S. embassy in Tehran and took US citizens hostage. Fifty-two Americans were ultimately held hostage for 444 days.

Last week, the US ambassador to Iraq held rare talks with his Iranian counterpart in Baghdad to discuss Iraq. There are no plans as yet for another meeting.

REUTERS SBC PM0013