The rescue of a two-year-old boy after 79 hours trapped in the rubble of a collapsed building in Hatay, Turkey, and several other people raised spirits among weary search crews.

But hopes were fading that many more would be found alive in the ruins of towns and cities.

The death toll across both countries has now surpassed the more than 17,000 killed in 1999 when a similarly powerful quake hit northwest Turkey.

A Turkish official said the disaster posed “very serious difficulties” for the holding of an election scheduled for May 14 in which President Tayyip Erdogan has been expected to face the toughest challenge in his two decades in power.

With anger simmering over the slow delivery of aid and delays in getting the rescue effort underway, the disaster is bound to play into the vote if it goes ahead.

Meanwhile the first United Nations convoy carrying aid to stricken Syrians crossed over the border from Turkey.

In Syria’s Idlib province, Munira Mohammad, a mother-of-four who had fled Aleppo after the quake, said: “It is all children here, and we need heating and supplies, last night we couldn’t sleep because it was so cold. It is very bad.”

Hundreds of thousands of people across both countries have been left homeless in the middle of winter.

Many have camped out in makeshift shelters in supermarket car parks, mosques, roadsides or amid the ruins, often desperate for food, water and heat.

About 40 per cent of buildings in the Turkish city of Kahramanmaras, epicentre of the tremor, are damaged, according to a preliminary report by Turkey’s Bogazici University.

At a service station near the Turkish town of Kemalpasa, people picked through cardboard boxes of donated clothes.

In the port city of Iskenderun, Reuters journalists saw people huddled round campfires on roadsides and in wrecked garages and warehouses.

Authorities say 6500 buildings in Turkey collapsed and countless more were damaged.

The death toll in Turkey rose to 17,134, the emergency management agency said.

In Syria, already devastated by nearly 12 years of war, more than 3200 people have died, according to the government and a rescue service in the rebel-held northwest.

In Turkey’s Maras, people camped inside a bank, taping a sheet in the window for privacy.

Others had set up on the grass median of a main road, heating instant soup on fires and wrapping themselves in blankets.

In Antakya, few petrol stations had fuel and kilometres-long queues stretched from those that did.

In the devastated Syrian town of Jandaris, Ibrahim Khalil Menkaween walked in the rubble-strewn streets clutching a white body bag.

He said he had lost seven members of his family including his wife and two of his brothers.

“I’m holding this bag for when they bring out my brother, and my brother’s young son, and both of their wives, so we can pack them in bags,” he said.

“The situation is very bad. And there is no aid.”

Turkish officials say 13.5 million people were affected in an area spanning roughly 450km from Adana in the west to Diyarbakir in the east.

In Syria, people were killed as far south as Hama, 250km from the epicentre.

A two-year-old boy was picked out of the rubble by a Romanian and Polish rescue team in Hatay 79 hours after the quake, video released by Turkey’s Humanitarian Relief Foundation (IHH) on Thursday showed.

The boy, wearing a blue, white and black striped sweater, cried as he was gently lifted from the hole where he had been trapped.

He was carried away on a blanket.

No other details were immediately available.

Another video from IHH showed a helmeted and dust-streaked rescuer weeping with emotion after successfully freeing a little girl from the rubble of a collapsed building in Kahramanmaras.

-AAP