Several hundred Iranian exiles departed Camp Ashraf, where Iranian opposition members have been based for decades, for a UN-approved site near Baghdad on Saturday, a legal adviser to the exiles said.
The move is part of a December 25 deal between the UN and Iraq, which was reached after extensive talks, under which around 3,400 Iranians opposed to the regime in Tehran will be moved to a new location called Camp Liberty, as part of a process that aims to see them resettled outside Iraq.
Iraq had previously aimed to close Camp Ashraf in Diyala province by the end of 2011, but Iraqi premier Nuri al-Maliki said in December that his government had agreed to extend the deadline to April.
Three hundred and ninety seven exiles departed in 18 buses beginning about 1:30 am on Saturday (2230 GMT on Friday), escorted by Iraqi security forces, Behzad Saffari, the legal adviser for residents of the camp, told AFP by telephone.
The departure followed a lengthy search process that Saffari said began around 2:00 pm (1100 GMT) on Friday, and continued until 1:15 am on Saturday (2215 GMT on Friday).
"They search all the bags, every single item," said Saffari, who arrived in Ashraf ahead of the US-led invasion of 2003 and was travelling with the group to Camp Liberty, near Baghdad airport.
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He said that Iraqi forces had raised objections to items including cameras and cooking knives, making for a lengthy process.
"It shows that they just want to be difficult," Saffari said. "It's been a long wait."
The late dictator Saddam Hussein allowed the opposition People's Mujahedeen Organisation of Iran (PMOI) to set up Camp Ashraf during his 1980-88 war with Iran.
The left-wing PMOI was founded in 1960s to oppose the shah of Iran, but took up arms against Iran's new clerical rulers after the Islamic revolution of 1979.
According to the US State Department, which has blacklisted the PMOI as a terrorist organisation since 1997, members of the group have carried out a large number of attacks against Iranian targets, and also against Americans.
The PMOI announced in 2001 that it had renounced violence, and is seeking to have the terrorist designation lifted.