But General David Petraeus, the head of U.S. Central Command and former commander of American forces in Iraq, said it was difficult to determine what role Iran's Revolutionary Guards might have played in the abduction of Moore and four bodyguards from an Iraqi Finance Ministry building in Baghdad.
"I am on the record as having said that our intelligence assessment is that he certainly spent part of the time, at the very least, in Iran, part of the time he was a hostage," Petraeus told reporters on Friday in Baghdad.
Britain's Guardian newspaper reported this week that Iran's Revolutionary Guards Corps led the kidnapping operation, and that Moore was seized because his computer work would have shown that large amounts of aid money flowing to Iraq were being diverted to Iranian-backed militia groups in Iraq.
The British Foreign Office said there was nothing to substantiate the report that Iran orchestrated the abduction. It also played down reports the hostages were taken to Iran.
British officials have said they believe the Shi'ite militant group Asaib al-Haq, Leagues of Righteousness, may have been involved in the kidnapping.
Moore was kidnapped in May 2007 at the height of sectarian bloodshed that killed tens of thousands of people following the 2003 U.S.-led invasion of Iraq. He was released on Wednesday and is expected to return to Britain very soon, possibly on Friday.
The bodies of three of the four bodyguards have since been handed over to British authorities, who believe the fourth is also dead.
The Guardian cited an unidentified former Iranian Revolutionary Guards officer as saying the operation was carried out by the al-Quds force, which specializes in foreign operations on behalf of Iran.
"It is difficult to say what role the Revolutionary Guards, and in particular the Quds force element, played in that," Petraeus said at a news conference after a ceremony at Saddam Hussein's al-Faw Palace, now part of a U.S. military base, to mark the official end to the multinational force in Iraq.
Since July, U.S. forces have been the only troops left of the original "coalition of the willing" assembled by then-U.S. President George W. Bush for the 2003 invasion of Iraq.
The United States plans officially to end combat operations in Iraq in August and to reduce its force from 110,000 now to fewer than 50,000 by that time.
(Editing by Tim Pearce)
