The first UN aid flight from Iraq landed in northeastern Syria on Sunday with badly needed supplies, after a winter storm delayed it for several days, the United Nations said.

UN aid agencies have "started airlifting urgently needed humanitarian aid from Arbil, Iraq, to Qamishli in northeast Syria as displaced families start to face one of the harshest winters ever," a UN statement said.

The first flight chartered by the UN World Food Programme (WFP) "landed today in Qamishli airport," and "WFP plans to use 11 more airlifts to move enough food to feed over 30,000 people for one month," it said.

WFP plans to send a total of some 400 tonnes of aid, while UN refugee agency UNHCR will send 300 tonnes of relief items "intended to help some 60,000 displaced people," it said.

And children's agency UNICEF "is sending a plane-load of health kits, water and sanitation supplies."

"Two planes are contracted to do 23 rotations over the next 10 days between the two countries," the UN said. "It is the first humanitarian airlift of supplies from Iraq into Syria since the crisis in Syria erupted in March 2011."

Road access into Hasakeh province in northeastern Syria has become dangerous, and there had not been any major overland deliveries of aid to the area since May, meaning that other means were needed.

The airlift, which has the go-ahead from both the Syrian and Iraqi governments, had been expected to begin on Thursday, but was delayed by a storm that shut down Qamishli's airport.

Amin Awad, who heads the UNHCR Syria response, said the original plan was for aid to be transported into northern and northeastern Syria by truck, but "there was a shift in the elements that controlled that road and the border and we shifted to an airlift."

But he added that airlifting aid would not be sustainable in the long run.

Meanwhile, the UNHCR plans to spend $195 million (142 million euros) to help "winterise" Syria and the surrounding countries.

As part of the programme, it has begun distributing items such as isolation tents, plastic sheeting and warm clothing, especially for children and other vulnerable people, as well as cash for fuel, Awad said.

The civil war between forces loyal to Syrian President Bashar al-Assad and rebels seeking his overthrow has raged for 33 months and killed more than 126,000 people.

But Kurdish-majority areas of the country's northeast were relatively quiet until clashes broke out this year between Kurds and jihadist rebels, pushing tens of thousands of Syrian Kurds across the border into Iraq's autonomous Kurdistan region.

According to UNHCR, Iraq's three-province autonomous Kurdistan region, from which the aid flights will depart, hosts more than 200,000 registered Syrian refugees -- the vast majority of those who are in Iraq.