The Iraqi High Tribunal has ordered the release of 15 officials from Saddam Hussein's regime, after finding no charges to bring against them, an official in the justice ministry said on Tuesday.

Three have already been liberated, including Mahmud Faraj Bilal al-Samarrai, a scientist implicated in Iraq's weapons of mass destruction programme under Saddam, who surrendered to the CIA in May 2003.

Former Iraqi trade minister Mohammed Mahdi al-Saleh was freed in March. He was number 35 among the most wanted officials by US forces following the 2003 US-led invasion, and was arrested on April 23, 2003.

And Hamed Yussef Hamadi, who served under Saddam as information and culture minister, then culture minister after the two ministries were split, and also as secretary of the presidency, was released in April.

"The decision was taken on April 5 by the Iraqi High Tribunal to free 12 other officials one by one after a final check," the justice ministry official said.

The remaining 12 include Hashem Hassan al-Majid, the governor of Babil province and the brother of "Chemical Ali," who was executed in 2010, and Fadel Salfij al-Azzawi, the governor of Salaheddin province at the time of the 1982 Dujail massacre.

Also to be released are the chief of the air force at the time of the Gulf War, General Muzahem Saad Hassan al-Tikriti, Latif Mahal Hamud, the former governor of Basra province, and Ogla Abed Sigar, a former high-ranking official in the now-disbanded Baath party.

"The 12 will be released today from Kadhimiya prison," said Badie Aref, a lawyer who has represented a number of Saddam-era officials, including former deputy prime minister Tareq Aziz.

The US military transferred 200 officials it held to Iraqi control before the departure of US troops at the end of last year.