By Sadeq Saba
BBC regional analyst
The People's Mujahideen opposed Iran's Government
United States military officials in Iraq have reportedly reached a disarmament deal with a heavily armed Iranian opposition group based in camps north-east of Baghdad.
The group, known as the People's Mujahideen of Iran, was backed by the former Iraqi leader, Saddam Hussein, and it is considered a terrorist organisation by Washington.
An American general who conducted the negotiations said the group would gather its fighters in camps under the control of the US army.
The disarmament deal came after two days of negotiations between a top American military commander, General Ray Odierno, and leaders of the People's Mujahideen.
General Odierno has been quoted as saying that the Iranian opposition fighters will withdraw into their camps under the control of the US-led forces.
He said the deal was not a surrender but an agreement to disarm.
Earlier, the US military had issued an ultimatum demanding that the Iranian group disarm or be destroyed.
Details of the deal are not available and it is not clear whether the group will be able to keep some of its light weapons for self-defence against Iraqi Shia groups close to the Iranian Government.
The American general said the final status of the Iranian opposition group would be decided by Washington.
On Friday, the Iranian fighters handed over all of their checkpoints to US forces, as part of a ceasefire agreed last month.
The People's Mujahideen is the most powerful external opposition to Iran's ruling clergy with an estimated 5,000 heavily-armed fighters.
Although their camps were bombed by the Americans during the war in Iraq, some members of the Bush administration apparently believe that Washington should use the group as a way of putting pressure on the Tehran government.
But other US officials argue that Washington should not work with groups which it designates as terrorist.
The Iranian Government had criticised the initial American ceasefire agreement with the group as a double standard in fighting terrorism.
But the latest disarmament deal could benefit Tehran.