• The US Geological Survey said the 7.8 magnitude tremor struck at 04:17 local time (01:17 GMT) at a depth of 17.9km (11 miles) near the city of Gaziantep.
• Rescue teams are searching for survivors after a devastating earthquake shook Turkey and Syria, killing hundreds of people.
A powerful earthquake has struck south-eastern Turkey, near the Syrian border, killing more than 1,000 people as they slept and trapping many others.
The US Geological Survey said the 7.8 magnitude tremor struck at 04:17 local time (01:17 GMT) at a depth of 17.9km (11 miles) near the city of Gaziantep.
Hours later, a second quake, which had a magnitude of 7.5, hit the Elbistan district of Kahramanmaras province.
So far, more than 900 people have died in Turkey and 500 in Syria.
Turkey's President Recep Tayyip Erdogan said the death toll there was now 912.
The Syrian health ministry said 371 people had died in the provinces of Aleppo, Latakia, Hama and Tartus.
The White Helmets rescue group, which operates in rebel-controlled areas of north-western Syria, said on Twitter that at least 147 people had died there.
Many buildings have collapsed and rescue teams have been deployed to search for survivors under huge piles of rubble.
Among the buildings destroyed was Gaziantep Castle, a historical landmark that had stood for more than 2,000 years.
The second quake, which struck at 13:24 local time (10:24 GMT), had its epicentre about 80 miles north of the original tremor in the Pazarcik district of Kahramanmaras province.
An official from Turkey's Disaster and Emergency Management Authority said it was "not an aftershock" and was "independent" from the earlier quake.
At least 70 deaths had already been reported across Kahramanmaras following the first quake, while 80 people were killed in Gaziantep.
Turkish Interior Minister Suleymon Soylu said 10 cities were affected by the initial quake, including Hatay, Osmaniye, Adiyaman, Malatya, Sanliurfa, Adana, Diyarbakir and Kilis.
At least 5,385 people were injured in Turkey and 1,000 in Syria.
A BBC Turkish correspondent in Diyarbakir reported that a shopping mall in the city collapsed.
The tremor was also felt in Lebanon and Cyprus.
"I was writing something and just all of a sudden the entire building started shaking and yes I didn't really know what to feel," Mohamad El Chamaa, a student in the Lebanese capital, Beirut, told the BBC.
"I was right next to the window so I was just scared that they might shatter. It went on for four-five minutes and it was pretty horrific. It was mind-blowing," he said.
Rushdi Abualouf, a BBC producer in the Gaza Strip, said there was about 45 seconds of shaking in the house he was staying in.
Turkey lies in one of the world's most active earthquake zones.
In 1999, more than 17,000 people were killed after a powerful tremor rocked the north-west of the country.