UNITED NATIONS, Federal and regional authorities in Iraq, together with the UN Children's fund (UNICEF) and the World Health Organisation (WHO), have launched a 12-day campaign, to immunise some 800,000 children under the age of five, against polio, rubella and measles, China's Xinhua news agency reported, UN spokesman as saying here.

"The campaign started on Dec 19, and targets children in Anbar, Salahaddin and Kirkuk governorates, as well as, newly retaken areas in Ninewah governorate, including displaced children living in camps," UN spokesman, Stephane Dujarric said, at a daily news briefing here.

The campaign forms part of the vaccination strategy, in the context of the ongoing Mosul operations; some 45,000 children affected by the Mosul operations will be receiving vaccines.

Iraq was removed from the list of polio-infected countries in May 2015, but there remain resurgence risks, due to surveillance and immunisation coverage gaps in conflict zones, the spokesman said.

"This will be the first time in two years that some of these children are receiving vaccines," Dujarric said.

On Oct 17, Iraqi Prime Minister, Haider al-Abadi, who is also the commander-in-chief of the Iraqi forces, announced the start of a major offensive to retake Mosul, the country's second largest city, in a bid to liberate the

northern Iraqi city, the last major Daesh stronghold in Iraq.

Mosul, some 400 km north of the Iraqi capital of Baghdad, has been under Daesh control since June, 2014, when Iraqi government forces abandoned their weapons and fled, enabling the militants to take control of parts of Iraq's northern and western regions.