Snow blanketed eastern Turkey Thursday, complicating rescue efforts and bringing more misery for the thousands left homeless by a devastating earthquake as the death toll surged past 500.

Ninety-one hours after disaster struck in the eastern province of Van, rescuers pulled a 19-year-old from the rubble in the town of Ercis but the prospects of finding more people alive were fading fast.

After the government acknowledged failings in the initial rescue efforts, help from abroad was beginning to arrive, including an aid plane from Israel.

But in a sign of the disillusionment with the help they had received so far, some families who had been staying in tents began returning to their homes despite warnings that they were still at risk of collapse from aftershocks.

Many families have been forced to sleep in overcrowded tents or even out in the open around fires as the temperatures drop to below freezing.

In its latest damage assessment bulletin, the prime minister's emergency unit said that 523 people were now known to have died after the 7.2 magnitude quake struck. A further 1,650 had been injured in the disaster, it added.

A total of 185 people had been pulled out of the wreckage, officials said.

The latest survivor to have beaten the odds, a student named Mohammed, was rescued from the rubble of a five-storey building, the NTV news channel reported.

He was rescued by an emergency crew who travelled to Ercis from Malatya, a distance of around 570 kilometres.

But with the hopes of finding more survivors receding, attentions were focusing increasingly on how to help those who had lost their homes.

The arrival of an Israeli plane carrying five pre-fabricated homes to provide shelter was a powerful symbol of the change of heart by the government which had initially refused help from abroad.

Relations between Turkey and Israel have been toxic in recent months in the wake of a deadly raid by Israeli commandos last year on an aid vessel bound for the Gaza Strip.

"Three more planes loaded with aid supplies will come to Turkey within two days," Nizar Amer, an official from the Israeli embassy in Ankara, told the Anatolia news agency.

A 150-person rescue team from Azerbaijan was already in the quake zone, becoming the first foreign group to show up in the earthquake region in eastern part of the country.

"Turkey's pain is our pain. We are very sad with what we have seen here," said 24-year old Ramil Aliyev from the Azerbaijani fire-fighter team.

"My team has recovered 18 survivors from the rubble but mostly we have been bringing bodies," added Aliyev.

After widespread overnight snowfalls in the region, forecasters said that the weather pattern would remain the same until the end of the week.

Huseyin Celik, deputy head of the governing Justice and Development Party (AKP), said that the earthquake had affected 700,000 people in the region and a total of 115,000 tents were needed.

There have been frequent complaints among residents of the mainly Kurdish region that the Ankara government would have acted faster if disaster had struck elsewhere.

"We did not discriminate between Turks, Kurds or Zaza people... We said that they are all our people," Erdogan said on Wednesday as he defended his government's handling of the aid operation.

But the revelation from the Turkish Red Crescent that 17 aid trucks had been raided highlighted the sense of despair among survivors.

Ahmet Lutfi Aker, the national head of the organisation, told AFP that the trucks had been looted both in the provincial capital Van and in Ercis.

Locals in Ercis recounted seeing the driver of one of the trucks assaulted before his attackers made off with food and blankets.