Iraqi President Jalal Talabani says the main Sunni political bloc will rejoin the Shi'ite-led ruling coalition after quitting the government last year.

After meeting with visiting U.S. Secretary of State Condoleezza Rice Sunday, Mr. Talabani said the Sunni bloc has put forward a list of candidates for Prime Minister Nouri al-Maliki's Cabinet.

Rice praised Iraq's Sunni Arab, Shi'ite and Kurdish leaders for working together in politics and backed Iraq's crackdown on militias.

Rice's unannounced visit to Baghdad came hours after radical Shi'ite cleric Moqtada al-Sadr threatened all-out war against the Iraqi government unless attacks against his supporters end. She responded to the threat by saying it is all-out war for anybody but al-Sadr, who she said is sitting safely in Iran while his followers can go to their death.

The top U.S. diplomat later met with Mr. Maliki and other top Iraqi officials before heading to Bahrain and Kuwait.

Earlier, the U.S. military said violence in Baghdad's Sadr City district, Moqtada al-Sadr's stronghold, has increased over the past days, with U.S. troops killing 20 gunmen.

In the southern city of Nasiriyah, the military said Iraqi security forces killed 40 Shi'ite militants and arrested 40 others, and found a large amount of weapons and ammunition.

On Saturday, Iraqi troops seized control of Sadr's Mahdi Army militia in the southern city of Basra. Iraq's prime minister ordered a crackdown on armed groups in Basra last month.

In other violence Sunday, police said gunmen kidnapped at least four people, including two university students, on a highway north of Baquba in central Iraq.

And, an Iraqi child was killed in Baghdad by an improvised explosive device. A U.S. military statement says the device appeared to be targeting Iraqi police in the New Baghdad district.

Some information for this report was provided by AFP, AP and Reuters.