A strong earthquake struck southeastern Turkey and neighbouring Syria in the early hours of Monday, devastating cities and killing and injuring thousands.

Here's what we know about the disaster so far:

- When and where -

The first 7.8 magnitude quake occurred at 04:17 am (0117 GMT) at a depth of about 18 kilometres (11 miles) near the Turkish city of Gaziantep, which is home to around two million people, the US Geological Survey said.

It was followed by a slightly smaller 7.5 magnitude tremor and many aftershocks.

The UN's cultural agency UNESCO said on Tuesday it was ready to provide assistance after two sites listed on its World Heritage list in Syria and Turkey sustained damage in the devastating earthquake.

As well as the damage to the old city of Syria's Aleppo and the fortress in the southeastern Turkish city of Diyarbakir, UNESCO said at least three other World Heritage sites could be affected.

"Our organisation will provide assistance within its mandate," said UNESCO director general Audrey Azoulay.

The energy industry must play a role in the campaign to tackle global warming, the president of this year's UN climate talks said on Tuesday, denying any "conflict of interest".

Sultan Al Jaber, who heads oil giant ADNOC and is the United Arab Emirates' special envoy for climate change, also called for "policies that are pro-growth and pro-climate".

"The energy transition will require every segment of society working together in an inclusive effort, and that surely means including the efforts of the energy industry," he told the India Energy Week conference in Bengaluru.

In the Turkish city of Sanliurfa, survivors of the massive quake that has wreaked death, destruction and havoc on the region face an invisible but powerful threat -- hunger.

As the morning sun illuminates the sky, Sanliurfa's cracked streets look empty. The mercury is only just above freezing, but it feels much colder.

Like their neighbours in the other nine provinces hit by Monday's 7.8-magnitude quake and its frightening aftershocks, the people of Sanliurfa are focused on basic survival.

Heartrending scenes of a newborn plucked alive from the rubble and a broken father clutching his dead daughter's hand have laid bare the human cost of the earthquake in Syria and Turkey that by Wednesday had claimed over 9,500 lives.

For two days and nights since the 7.8 magnitude quake an impromptu army of rescuers have worked in freezing temperatures to find those still entombed among ruins in several cities either side of the border.

Up to 23 million people could be affected by the massive earthquake that has killed thousands in Turkey and Syria, the WHO warned on Tuesday, promising long-term assistance.

"Event overview maps show that potentially 23 million people are exposed, including around five million vulnerable populations," the World Health Organization's senior emergencies officer Adelheid Marschang said.

"Civilian infrastructure and potentially health infrastructure have been damaged across the affected region, mainly in Turkey and northwest Syria," she said.

Prisoners mutinied in a northwestern Syria prison Monday following a deadly earthquake, with at least 20 escaping the jail holding mostly Islamic State group members, a source at the facility told AFP.

The military police prison in the town of Rajo near the Turkish border holds about 2,000 inmates, with about 1,300 of them suspected to be IS fighters, said the source.

The prison also holds fighters from Kurdish-led forces.

British author Salman Rushdie said he finds it "very difficult" to write after being stabbed last year, in an interview published Monday ahead of the release of his new novel "Victory City."

Rushdie, whose "epic tale" of a 14th-century woman who defies a patriarchal world to rule a city hits US shelves on Tuesday, said the attack had scarred him mentally.

"There is such a thing as PTSD you know," the 75-year-old told the New Yorker magazine in his first interview since the August 12 stabbing at a conference in Chautauqua in upstate New York.

A stream of cars crawled north out of the shattered city of Sanliurfa, taking traumatised residents a little further from the scene of Turkey's most powerful earthquake in decades.

On the opposite side of the road, a distraught family walked in the freezing rain, their belongings piled into a stroller, looking for shelter to spend the night.

Sanliurfa, one of the bigger cities of southeastern Turkey, was hammered by the massive quake that claimed at least 3,000 lives across the mostly Kurdish region and neighbouring Syria.

British author Salman Rushdie has said he finds it "very difficult" to write after being stabbed in New York last year, in his first interview since the attack.

Rushdie told the New Yorker, in an article published Monday, that the stabbing on stage at an event had left him with mental scars.

"There is such a thing as PTSD you know," the 75-year-old said.