Five British civilians kidnapped in Baghdad last month are being held by a group trained, funded and armed by Iran, according to the US commander in Iraq.
General David Petraeus said he believed that the Britons - four security guards and a consultant - were taken by a "secret cell" of the Mahdi Army, the Shia militia loyal to cleric Moqtada al-Sadr.
There had been repeated efforts to free the men, Gen Petraeus said, and "a very intensive effort" was in place to find the group who he believes were abducted in retaliation for the killing of Abu Qader, the militia's leader in Basra.
"We think that it is the same network that killed our soldiers in Karbala in an operation back in January," he said.
He said that the head of that network was killed less than a week before the Britons were captured by Mahdi Army members. He did not believe the fighters who captured the workers were ordinary "rank and file" members. "They are trained in Iran, equipped with Iranian [weapons], and advised by Iran," he told the Times. "The Iranian involvement here we have found to be much, much more significant than we thought before.
"They have since about the summer of 2004 played a very, very important role in training in Iran, funding, arming."