ISIS militants have killed scores in southern Iraq’s Dhi Qar Governorate that was visited by Prime Minister Haider al-Abadi earlier this week.
The attack has upset the relative calm in southern Iraq and left more than 75 people dead and around 90 injured.
Interior Ministry sources said that armed men opened fire at revelers in a restaurant near a security checkpoint and later detonated a car bomb.
But Reuters said there were three suicide attacks in the area.
Wearing security force uniforms and driving stolen army vehicles, the attackers targeted a police checkpoint and two restaurants on a highway near the city of Nassiriya, using car bombs and suicide vests, security sources told Reuters.
ISIS terrorist group claimed responsibility in a statement on its Amaq news agency.
The head of Nassiriya's health directorate, Jassim al-Khalidi, said the city's hospital had received 50 bodies and the death toll could rise because some of the wounded were in critical condition.
Hospital sources said at least 10 Iranian pilgrims, who were visiting holy Shi'ite shrines, were among the dead.
The deadliest attack was at a restaurant west of Nassiriya. "One attacker blew up his suicide vest inside the crowded restaurant while a group of other gunmen started to throw grenades and fire at diners," said police colonel Ali Abdul Hussain.
Police sources said some police officers had died in the checkpoint attack, but the toll from that incident remained unclear.
Security sources said forces were placed on alert in most of the southern provinces, including the oil city of Basra, in case of similar attacks.
The attack in Nassiriya came as several Iraqi cities were rocked on Thursday by bombings and acts of violence.