The United Nations has said millions of refugees in Syria need urgent help as freezing winter temperatures continue to make living conditions unbearable.

Snow storms and sub-zero temperatures have swept through the many refugee camps in northwest Syria where thousands of families are seeking refuge from ongoing fighting.

Speaking to Sky News, the UN deputy co-ordinator for Syria, Mark Cutts, called on the international community not to forget the country.

Freezing temperatures and snow have swept across many camps in Syria.

"I don't think the international community is doing enough to help these people," Mr Cutts said. "They are some of the most vulnerable people in the world."

He added: "People are really suffering and dying in these conditions. The numbers are staggering. Almost three million displaced, three thousand tents that were badly damaged or completely destroyed."

Thousands of families are seeking refuge from ongoing fighting in Syria.

Mr Cutts said the challenge was to "relocate people to better, safer conditions", while some were already being accommodated in mosques, schools, and other public buildings.

"These are people who depend on food aid," he said. "We had to do a lot of work to open up the roads, get mobile health teams to these places. It's all on a huge scale."

With wood sodden by the weather, people are forced to burn plastic on fires inside tents to stay warm, resulting in toxic fumes which then make children sick.

At least two babies have frozen to death in their tents.

At least two babies have frozen to death in their tents. One of those was Aminah al Salamah. Her father, Mohammed, told us how he found her.

"When we got up in the morning, I saw her like a piece of wood," he said. "We took her to a clinic that transferred us to the hospital. They called seven to eight ambulance cars, but unfortunately no car came. So I was angry and I took her by motorbike as it was raining.

"My wife stayed at hospital. At 4am she called me that the doctor said 'your daughter died'. In the morning I went there. I took her and brought her home by motorbike."

Local hospitals - many of them destroyed by war - are full and struggling to treat the huge number of sick children who need help. Most of them are under two months old and extremely weak.

They have chest infections and are struggling to breathe through a combination of the extreme cold weather and inhaling the fumes of burning plastic.

The UN deputy co-ordinator for Syria, Mark Cutts, said the international community was not doing enough.

"There is no vacancy in the hospital, neither in the wards nor in the incubator department," Dr Abd Al Basit Sulieman said.

"The first reason is the lack of support for more than 18 health facilities in the liberated north," he said.

"The second is more important as most of the kids who come to the hospital are from the camps - especially the ones who are one day old and two months.

"They come in a state of suffocation or semi-suffocation caused by bronchiolitis in addition to the use of waste or plastic materials for heating tents."