Karbala (Iraq) (AFP) - The Islamic State group's occupation of northern Iraq and the battle to defeat it has caused more than $100 billion worth of damage, Prime Minister Haider al-Abadi said Saturday.
He was speaking during a visit to Karbala, a city holy to Shiite Muslims, where millions of pilgrims gathered Friday to mark the annual Arbaeen commemoration.
"The damage caused by the IS occupation of Iraqi cities already amounts to more than $100 billion," Abadi said.
"That's just the damage to the economy and infrastructure."
IS, a radical Sunni group, seized around a third of Iraq and parts of Syria in a sweeping 2014 advance.
But its self-declared "caliphate" has since been decimated by multiple offensives and squeezed into a pocket of territory on the Iraqi-Syrian border.
Iraqi forces launched an operation Saturday to retake the last IS-held towns in Iraq, including the Euphrates valley town of Rawa and nearby villages.
The assault also aims to "clean open areas in the desert" of western Iraq, said Abadi, who is also head of the armed forces.
Arbaeen is one of the biggest religious festivals on earth and marks the end of the 40-day mourning period for the 7th-century killing of Imam Hussein by the forces of the Caliph Yazid -- a formative event in Shiite Islam.
Around 15 million pilgrims gathered in Karbala for this year's commemoration, including three million non-Iraqis, mostly Iranians, the province's security chief Qais Khalaf said Saturday.
The pilgrimage, under tight security, passed off without incident.
The expulsion of IS from Iraqi cities added an extra dimension to this year's pilgrimage, as the Sunni extremist group has repeatedly targeted Shiites.
Last year, a suicide bombing killed at least 70 mainly Iranian worshippers returning from the commemoration.