The members of the People's Mujahedeen, an exiled opposition group, were arrested by Iraqi police during a raid on Camp Ashraf, in Diyala province north of Baghdad, which left 11 camp residents dead.
"I released them; I said that they should go back to Camp Ashraf," Judge Ali al-Timimi told AFP, referring to a decision he delivered on Sunday.
A judicial official, speaking on condition of anonymity, said Iraqi authorities had refused to release the group because they considered them having illegally infiltrated Iraq.
"It … became clear that the allegations were unfounded from the start and were meant for covering up the crimes against humanity that took place in Ashraf," People's Mujahedeen spokesman Shahriar Kia said in an e-mailed statement.
Earlier this month, US Ambassador Christopher Hill vowed to press the Iraqi government, which the Mujahedeen say answers to Tehran, to live up to assurances to treat the residents humanely and make sure they are not repatriated to Iran.
The group was founded in 1965 in opposition to the shah of Iran. It has subsequently fought to oust the clerical regime which took power in the 1979 Islamic revolution.
The group set up Camp Ashraf in the 1980s — when former Iraqi dictator Saddam Hussein was at war with Iran — as a base to operate against the Tehran government.
