Rescuers pulled more survivors from rubble on Sunday, six days after one of the worst earthquakes to hit Turkey and Syria, as Turkish authorities sought to maintain order across the disaster zone and started legal action over some building collapses.

With chances of finding more survivors growing more remote, the toll in both countries from Monday's earthquake and major aftershocks rose above 28,000 and looked set to keep growing. It was the deadliest quake in Turkey since 1939.

Displaced residents in the Turkish city of Kahramanmaras, near the epicentre, said they had set up tents as close as they could to their damaged or destroyed homes in an effort to prevent them from being looted.

Facing questions over his response to the earthquake as he prepares for a national election that is expected to be the toughest of his two decades in power, President Tayyip Erdogan promised to start rebuilding within weeks.

In Syria, the disaster hit hardest in the rebel-held northwest, leaving many homeless for a second time after they were displaced by a decade-old civil war, though the region has received little aid compared to government-held areas.

The European Union's envoy to Syria urged Damascus not politicise issues of humanitarian aid, and rejected accusations that the bloc had failed to provide sufficient help to Syrians following the disaster.

"It is absolutely unfair to be accused of not providing aid, when actually we have constantly been doing exactly that for over a decade and we are doing so much more even during the earthquake crisis," Dan Stoenescu told Reuters.

In Turkey's southeastern province of Hatay, a Romanian rescue team carried a 35-year-old man named Mustafa down a pile of debris from a building, broadcaster CNN Turk said, about 149 hours after the quake.

"His health is good, he was talking," said one of the rescuers. "He was saying, 'Get me out of here quickly, I've got claustrophobia'."

SECURITY FEARS AND DETENTION ORDERS

Two German rescue organisations suspended work in Turkey on Saturday, citing reports of clashes between groups of people and highlighting concerns for security in the quake-hit areas.

Gizem, a rescue worker from the southeastern province of Sanliurfa, said she had seen looters in the city of Antakya. "We cannot intervene much, as most of the looters carry knives."

One elderly resident of Kahramanmaras said that gold jewelry in his home had been stolen, while in the port city of Iskenderun police had deployed at junctions of commercial streets with many phone and jewelry shops.

Erdogan has warned that looters will be severely punished.

The soundness of buildings has come into sharp focus in the aftermath of the quake.

Vice President Fuat Oktay said overnight that 131 suspects had so far been identified as responsible for the collapse of some of the thousands of buildings flattened in the 10 affected provinces.

"We will follow this up meticulously until the necessary judicial process is concluded, especially for buildings that suffered heavy damage and buildings that caused deaths and injuries," he said.

The earthquake hit as Erdogan faces presidential and parliamentary elections scheduled for June. Even before the disaster, his popularity was falling due to soaring inflation and a slumping Turkish currency.

Some people affected by the quake and opposition politicians have accused the government of slow and inadequate relief efforts early on, and critics have questioned why the army, which played a key role after a 1999 earthquake, was not brought in sooner.

Erdogan has acknowledged problems, such as the challenge of delivering aid despite damaged transport links, but said the situation had been brought under control. He has called for solidarity and condemned "negative" politicking.

ONCE IN A CENTURY DISASTER

Along the main road leading into the city of Antakya, where the few buildings left standing had large cracks or caved-in facades, traffic occasionally halted as rescue teams called for silence to detect signs of remaining life under the ruins.

U.N. aid chief Martin Griffiths described the earthquake as the region's worst event in 100 years, predicting on Saturday that the death toll would at least double.

He praised Turkey's response, saying his experience was that disaster victims were always disappointed by early relief efforts.

The quake ranks as the world's seventh deadliest natural disaster this century, its toll approaching the 31,000 from a quake in neighbouring Iran in 2003.

It has killed 24,617 inside Turkey, and more than 3,500 in Syria, where tolls have not been updated since Friday.

Turkey said about 80,000 people were in hospital, with more than 1 million in temporary shelters.

In Syria's government-controlled city of Aleppo, World Health Organisation chief Tedros Adhanom Ghebreyesus described the disaster as heartbreaking as he supervised some relief distribution and promised more.

Western nations have largely shunned President Bashar al-Assad during the war that began in 2011.