Twelve security personnel within the interior ministry have been arrested for allegedly supportive of sectarian violence in Iraq, said major Abdul Karim Khalaf, a spokesman for Iraq's interior ministry.

Iraqi officials said they are believed to be behind the 2006 killing of the sister of Tareq al-Hashemi, a Sunni who is one of Iraq's two vice presidents.

The violence that erupted in Iraq after the 2003 invasion has decreased in the past year, but suicide attacks are continuing.