The mission said that the deteriorating security situation in Mosul and surrounding areas, including Tal Afar and Diyala, continues to cause more displacement, Xinhua quoted UN spokesman Stephane Dujarric as saying.
UN agencies and their partners are setting up new sites and tents in Erbil, Dohuk and Suleimaniya in the northern region of Kurdistan to accommodate the growing influx of displaced families, Dujarric said.
The security situation in Iraq has continued to deteriorate following last week's capture of Mosul and other area by members the Islamic State of Iraq and the Levant (ISIL).
The violence has uprooted thousands of people and has been marked by numerous human rights violations.
The UN Refugee Agency (UNHCR) last week said that almost a million people have fled their homes since January.
At least half of them are children, the UN Children's Fund (UNICEF) confirmed Thursday, adding that many need water and sanitation support, immunization against polio and measles, and protection services.
Cargo planes carrying emergency supplies from UNICEF, the UN World Food Program (WFP) and the UN World Health Organisation (WHO) arrived in Erbil earlier this week carrying supplies, including tents, blankets, for more than 35,000 children.