Four US soldiers have been killed in Iraq, the US military reported on Wednesday amid further violence in the Iraqi capital, Baghdad, and beyond.
At least 11 people were killed throughout the country, including two who died after a Baghdad bomb blast.
A Baghdad university said three Sunni professors and a student kidnapped three days ago had been found dead.
Meanwhile Iraq's government said it planned to hold a regional peace conference in March, AFP reported.
Iran, Jordan, Kuwait, Saudi Arabia, Syria, Turkey, Egypt and Bahrain as well as the Arab League and the Organisation of the Islamic Conference were reported to have been invited.
On Wednesday the US military said a soldier died from injuries sustained during fighting in Salaheddin province.
It also announced that two soldiers and a marine died after being injured during operations on Tuesday in the Sunni-dominated Anbar province.
In other developments:
Three professors and a student, kidnapped from the law faculty of Baghdad's Nahrain university on Sunday, are found dead
A car bomb explodes in central Baghdad, killing at least two and wounding eight
A suicide bomber drives a lorry laden with fuel into the main gate of an Iraqi army base in Miqdadiya, some 50 miles (90km) north-east of the capital, injuring nine soldiers, Reuters reports
Two men are killed during an air strike carried out by a US helicopter in Mahmudiya, 20 miles (30km) south of Baghdad. The US military says the target was suspected insurgents planting a roadside bomb. Residents say the men were followers of radical cleric Moqtada Sadr who were marking the Ashura ritual.