By Stephen Kalin
BAGHDAD (Reuters) - Iraq's two main parliamentary lists including Sunni lawmakers suspended their activities on Saturday in protest at the killing of a prominent Sunni tribal leader and the kidnapping of a Sunni member of parliament the night before.
Sheikh Qassem al-Janabi and his son were shot dead along with at least six guards after gunmen stopped their convoy in south Baghdad. The sheikh's nephew, parliamentarian Zayed al-Janabi, was detained but later released.
The Interior Ministry said it would investigate the incident, which raised questions about the government's control over security in the capital, where safety measures were eased last week despite the proliferation of rival armed groups.
The attack also threatened to exacerbate the sectarian tensions that have undermined Iraq's response to Islamic State insurgents who seized large swathes of territory in the country's north and west last year.
"The Iraqiya Alliance and the National Coalition announce they are suspending their participation in sessions of the Council of Representatives as from today," lawmaker Ahmed al-Massari said in a statement broadcast on local television.
Lawmakers said the boycott would include all of the roughly 75 lawmakers in the two lists, including some Shi'ite members.
The statement blamed Prime Minister Haider al-Abadi and his ministers of defense and interior for "the breakdown of security and letting loose killers and outlaws to commit crimes of ethnic cleansing".
Sunni politicians and tribal leaders have accused Shi'ite militias organized under the government-run Hashid Shabi, or popular mobilization committee, of killing civilians and destroying their homes in Sunni districts recaptured from Islamic State, which itself has blown up and booby-trapped areas it once controlled.
Abadi, a moderate Shi'ite Islamist who has sought reconciliation between Iraq's Shi'ite and Sunni communities, and Grand Ayatollah Ali al-Sistani, Iraq's most senior Shi'ite cleric, have denounced such actions. Abadi promised an investigation into the allegations.
No group has claimed responsibility for Friday's attack, but Deputy Prime Minister Saleh Mutlaq called for the eradication of the Shi'ite militias, which operate freely in much of Iraq and have spearheaded the battle against Islamic State insurgents since the army nearly collapsed last summer.
"We must get rid of the militias, and weapons must be in the hands of the state," he told reporters before the victims were buried on Saturday.
"They want to bring down ... the voice of every patriot. This is a message we must understand: to take a stand against the militias and the outlaws."
(Reporting By Stephen Kalin; Editing by Kevin Liffey)