Rescuers have pulled more survivors from the rubble in Turkey as the death toll from the earthquake nearly a week ago rose above 33,000 on Sunday.

The toll from the magnitude 7.8 and 7.5 quakes that struck nine hours apart has risen to 29,605 in Turkey and more than 3,500 in Syria, where tolls have not been updated for two days.

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

Thousands of rescuers, paramedics and sniffer dogs have been working relentlessly to find survivors in southern Turkey, while parts of opposition-held Syria remain quiet.

Among the rubble in Syria, a heartbreaking message scribbled on a slab of concrete was reportedly left by those who did not survive: “We are dead. Thank you for letting us down”.

The northwest region has received little aid compared to government-held areas in Syria.

“We have so far failed the people in north-west Syria,” United Nations aid chief Martin Griffiths tweeted from the Turkey-Syria border, where only a single crossing is open for UN aid supplies.

“They rightly feel abandoned,” Mr Griffiths said, adding that he was focused on addressing that swiftly.

He will travel to the northern Syrian city of Aleppo on Monday to survey the damage and launch a United Nations appeal for Syria, which he hopes will cover both government and non-government zones of control.

More than six days after the first quake struck, emergency workers still found a handful of people clinging to life in the wreckage of homes that had become tombs for many thousands.

In the city of Antakya in southern Turkey, a team of Chinese rescuers and Turkish firefighters saved 54-year-old Syrian Malik Milandi after he survived 156 hours in the rubble.

A father and daughter, a toddler and a 10-year-old girl were among other survivors pulled from the ruins of collapsed buildings on Sunday, but such scenes are becoming rare.

At a funeral near Reyhanli, veiled women wailed and beat their chests as bodies were unloaded from lorries - some in closed wood coffins, others in uncovered coffins, and still others just wrapped in blankets.

Building quality in a country that lies on several seismic fault lines has come into sharp focus in the aftermath of the quake.

Turkish Vice President Fuat Oktay said 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 President Erdogan faces presidential and parliamentary elections scheduled for June.

His government has been criticised for a slow response, with critics questioning why the army was not brought in sooner.

Before the disaster, President Erdogan’s popularity had been falling due to soaring inflation and a slumping Turkish currency.

Erdogan has acknowledged problems, such as the challenge of delivering aid despite damaged transport links, but said the situation had been brought under control.

‘Put politics aside’ UN envoy in Syria says

In Syria aid from government-held regions into territory controlled by opposition groups has been held up, a UN spokesperson said.

A source from Islamist group Hayat Tahrir al-Sham (HTS) told Reuters the group would not allow any shipments from government-held areas and that aid would be coming in from Turkey to the north.

The UN is hoping to ramp up cross-border operations by opening an additional two border points between Turkey and opposition-held Syria for aid deliveries, spokesperson Jens Laerke said.

Several Arab countries have provided support to Syrian President Bashar al-Assadin the quake’s aftermath.

Western countries, which sought to isolate Assad after his crackdown on protests in 2011 and the outbreak of civil war, are major contributors to UN relief efforts across Syria but have provided little direct aid to Damascus during the civil.

The first shipment of European earthquake aid to government-held parts of Syria also arrived in Damascus on Sunday.

UN Syria envoy Geir Pedersen said in Damascus the United Nations was mobilising funding to support Syria.

"We’re trying to tell everyone: Put politics aside, this is a time to unite behind a common effort to support the Syrian people," he said.