The United Nations refugee agency said on Tuesday it was launching a major aid operation to get supplies to more than half a million people displaced by fighting in northern Iraq. Hundreds of thousands have fled their homes since fighters led by the militant Islamic State group swept through much of the north and west of Iraq in June, threatening to break up the country. A four-day airlift of tents and other goods will begin on Wednesday to Arbil, Iraq from Aqaba in Jordan, followed by road convoys from Turkey and Jordan and sea shipments from Dubai via Iran over the next 10 days, said UNHCR spokesman Adrian Edwards. "This is a very, very significant aid push and certainly one of the largest I can recall in quite a while," he told a news briefing in Geneva. "This is a major humanitarian crisis and disaster." The UNHCR estimates that a total of 1.2 million have fled their homes across Iraq this year. About 200,000 of them have settled in Iraq's Kurdistan region since August when the city of Sinjar and neighbouring areas were seized by Islamic State, according to UNHCR. At least 11,000 people from the Yazidi minority have taken shelter inside Iraq's war-torn neighbour Syria, and about 300 more are crossing the Peshkabour border every day, it said. "The fact that you see people fleeing via Syria to safety speaks very much to how desperate the situation is, particularly in Sinjar in the last few days," Edwards said. The initial aid shipments will contain 3,300 tents and 20,000 plastic sheets for shelter, 18,500 kitchen sets and 16,500 jerry cans, he added. They were being supported by Saudi Arabia, Britain, the United States and other donors.