The United States said Thursday that its release of five Iranian prisoners in Iraq was required under the U.S.-Iraq security accord and not a political gesture toward Tehran.  The five Iranians, held by U.S. forces since early 2007, were transferred to Iraqi custody on Thursday and immediately handed over to Iranian authorities.  

Officials here say the United States is concerned that the five Iranians might pose a threat to U.S. troops in Iraq, but that the handover to Iraqi authorities was an obligation under the U.S.-Iraq security agreement that took effect at the beginning of the year.

The five Iranians, detained in northern Iraq in January 2007, are believed to be linked to the elite Quds Force of the Iranian Revolutionary Guards and are suspected of aiding militants attacking U.S. and other foreign forces with sophisticated explosives.

The Iranian government has described the detainees - the so-called "Irbil Five" - as diplomats and has long contended their detention was illegal.

US State Department spokesman Ian Kelly  (File)

At a news briefing, State Department Spokesman Ian Kelly said U.S. forces released the five men in response to an official order by the Iraqi government for the handover of all third county nationals held by U.S. forces.

Kelly said the U.S. military complied, consistent with its respect for Iraqi sovereignty and the security agreement.  The five were then handed over almost immediately to staff members of the Iranian embassy in Baghdad, despite what the spokesman said were continuing U.S. concerns about their affiliation.

"These detainees in question were associated with the Iranian Revolutionary Guards," said Ian Kelly. "And, of course, we have concerns, particularly about the part of the Iranian Revolutionary Guards they were associated with, which is the Quds force, which has been involved in training and supporting Iraqi militant groups.  But again, this is something that we agreed to with the Iraqi government and so we are maintaining our obligation to them."

In Baghdad, Iraqi Foreign Minister Hoshyar Zebari called the release "a good initiative" that could encourage dialogue between the United States and Iran.

But under questioning here, spokesman Kelly told reporters that the handover was exclusively a function of U.S. legal obligations to Iraq - not part of a prisoner release deal with or political gesture toward the Tehran government.

There had been suggestions that the handover of the five Iranians might have been a delayed quid pro quo for Iran's release of detained Americans - most recently, journalist Roxana Saberi who was freed in May.  Kelly said such speculation is incorrect.