BAGHDAD (AFP) - The Iraqi army arrested the alleged military leader of Al-Qaeda's offshoot in Iraq, Mikhlif Mohammed Hussein al-Azzawi, and three of his acolytes in a raid on Wednesday, the defence ministry said. The arrests come less than three weeks after the killing of Al-Qaeda leader Osama bin Laden in a raid by US special forces in Pakistan, and just a day after Iraq announced that "collaboration" contributed to a mutiny by suspected insurgents being held in a Baghdad jail that killed six policemen. The accused insurgent, also known as Abu Radhwan, was detained along with three other suspected leaders of the Islamic State of Iraq, spokesman Major General Mohammed al-Askari told AFP. "These are four major leaders of Al-Qaeda in Iraq, and they are four of the most dangerous, most wanted figures in Al-Qaeda," Askari said. Askari said the operation to detain the group was carried out by the Iraqi army at around 1:30 am (2230 GMT) on Wednesday, west of Samarra, 110 kilometres (70 miles) north of Baghdad. The others arrested were Mohammed Saad Muzzaham al-Daraji, the suspected head of the Al-Qaeda branch's assassinations unit, Fawzi Abbas Ali al-Badri, who is also known as Abu Abdulrahman and who Askari said was primarily charged with kidnapping soldiers with a view to killing them and burning their bodies. Soldiers also detained Qassim Mohammed Taha, who is wanted in connection with a brazen March 29 attack in the city of Tikrit, north of Baghdad, in which 58 people were killed, the deadliest attack in Iraq since August. Askari added that 18 other insurgents were arrested in a separate raid in northern Nineveh province, near Iraq's border with Syria, but did not specify who exactly was detained. The arrests follow an announcement Tuesday by Iraq's interior ministry that "negligence and collaboration" contributed to the May 7 mutiny at a Baghdad prison in which six policemen, including a brigadier general, and 11 inmates were killed. "The incident was planned," the ministry said in a statement. "The negligence and collaboration of some infiltrators helped provide the tools of the crime by bringing materials to the detainees." Violence is down across Iraq since its peak in 2006 and 2007, but attacks remain common. A total of 211 people were killed in April as a result of attacks, according to official figures.