Live updates: follow the latest news on the Turkey and Syria earthquake
Turkey on Tuesday announced a three-month state of emergency and the World Health Organisation warned 23 million people could have been affected by Monday's earthquake that has now killed more than 5,000 people.
The organisation also issued a stark warning that the death toll could surpass 20,000.
The toll from the 7.8-magnitude earthquake that has left widespread devastation across eastern Turkey and northern Syria continued to rise sharply on Monday, with the UN saying “thousands” of children may have been among those killed.
By Tuesday evening, Turkey said at least 3,400 people have been killed while in Syria at least 1,600 are dead.
“It is now a race against time,” said WHO director general Dr Tedros Adhanom Ghebreyesus. The UN health agency was sending urgently required aid to the area, he added.
“We're mobilising emergency supplies and we have activated the WHO network of emergency medical teams to provide essential health care for the injured and most vulnerable,” he said.
International support was pouring in on Tuesday, with many countries sending teams of specialist rescuers and equipment as well as financial support for the relief effort. President Sheikh Mohammed ordered $100 million of aid to be split between Turkey and Syria.
The situation is particularly dire in northern Syria, which has already been decimated by years of civil war.
“This is a crisis on top of multiple crises in the affected region,” said Adelheid Marschang, WHO senior emergency officer at the organisation's board meeting in Geneva.
However, the sole border crossing used to shuttle life-saving aid from Turkey was itself “a disaster zone”, the UN said.
A representative said UN aid to north-western Syria was temporarily halted.
“Some roads are broken, some are inaccessible. There are logistical issues that need to be worked through,” Madevi Sun-Suon of the UN Office for the Co-ordination of Humanitarian Assistance told Reuters.
The scale of damage to infrastructure was also becoming clear on Tuesday, as hundreds of shipping containers continued to burn at Turkey's Iskenderun Port, shutting down operations and forcing freight liners to divert vessels to other ports.
Turkey's maritime authority said that the port, located on the Mediterranean coast in the southern province of Hatay, was damaged due to the earthquake that struck Turkey and neighbouring Syria. Iskenderun is home to heavy industries such as steel and is one of the two major container hubs on Turkey's southeastern shores.
While rescue teams from 70 countries fly in to bolster the 24,400 emergency personnel now working on the ground in Turkey, in Syria people continued to dig through the debris with bare hands.
Syria's volunteer opposition rescue workers, known as the White Helmets, have appealed for heavy machinery to help.
“There are a lot of efforts by our teams but they are unable to respond to the catastrophe and the large number of collapsed buildings,” the group's head Raed Al Saleh told Reuters.
Without urgent aid, expert rescue teams and better access, the death toll could continue to rise sharply.
“The earthquakes that hit southern Turkey and northern Syria early yesterday morning may have killed thousands of children,” Unicef spokesman James Elder said in a press briefing on Tuesday.
Cities of eastern Turkey before the earthquake — in pictures
Almost 6,000 buildings have been destroyed in Turkey. Bodies continue to be removed from under rubble in both countries.
In the impoverished rebel-held north-western regions of Syria, resources for assistance are scarce, in a country that is in its 12th year of war.
The WHO said it was “especially concerned” about areas in Turkey and Syria where communication is difficult.
Aside from the rising death toll, Dr Tedros said plummeting temperatures are making matters worse.
“Numbers do not tell us about the perilous situation that many families now face, having lost everything, forced to sleep outside in the middle of winter,” he said.
Nine hours after the first quake, another 7.5-magnitude aftershock hit Turkey, one of more than 200 aftershocks recorded since the initial disaster.
“More aftershocks are certainly expected, given the size of the main shock,” said Alex Hatem, a US Geological Survey research geologist.
“We expect aftershocks to continue in the coming days, weeks and months.”
Damage to infrastructure, roads and communication lines “continues to hamper access and other search and rescue efforts”, Dr Tedros said.
In Syria, Abdelrazzaq Al Nahban said his younger brother died after being alive under rubble for 15 hours without medical assistance.
“There was nobody to take him to the hospital. We are incapable of doing anything,” he wrote on Facebook.
Many more like him shared their plight as aid became increasingly difficult to bring through from Turkey.
So far, 17 EU countries have offered assistance to Turkey in the form of search and rescue and medical emergency teams. More than 1,100 rescuers and 72 search dogs are heading to Turkey, with the first batch arriving on Monday.
Russia, China and India are also sending assistance in the form of rescuers and humanitarian aid, while Ukraine's Foreign Minister Dmytro Kuleba said his country was looking for spare capacity to assist, despite the war in the country.
Lebanon and Palestine have offered assistance despite their own dire finances.
Israel is also dispatching aid to Turkey. Prime Minister Benjamin Netanyahu also said he was ready to send aid to Syria, although Damascus denied that it had asked for help. Syria and Israel have no official diplomatic relations. Iran and Iraq have also sent aid shipments.
