At least 50 people were killed, including some Iranian pilgrims, and over 80 more got injured, when the Islamic State jihadists carried out twin attacks in the southern Iraqi city of Nasiriyah.
A auto bomb in the same area targeted a security checkpoint shortly afterwards, according to interior ministry spokesman Saad Maan.
He added that the death toll could rise due to the critical condition of some of the wounded.
That was followed by two suicide bombers, including one driving an explosives-laden auto, he said.
Security sources said the attackers were disguised as members of the Hashed al Shaabi, the mainly Shia paramilitary units which fight alongside the army against IS.
A large number of the fatalities were recorded in the capital province of Baghdad, where 45 civilians were killed and 135 others wounded during the same period.
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The area targeted is used by pilgrims and visitors from neighbouring Iran headed for the holy cities of Najaf and Karbala further north, although Dhiqar has previously been spared the worst of the violence.
Police sources said some police officers had died in the checkpoint attack, but the toll from that incident remained unclear.
Iraqi and Kurdish security officials told Reuters the Sunni militants were likely to wage a guerrilla war in Iraq after devastating territorial losses they suffered from Iraqi forces.
The attack occurred as Iraqi forces battled to defeat ISIS terrorists in areas under their control.
Islamic State claimed responsibility in a statement on its Amaq news agency.