British search and rescue specialists are traveling to Turkey to help search for survivors after the earthquake that killed more than 2,300 people.
A team of 76 rescuers is flying to Turkey on Monday evening.
Two 7.8 and 7.5 quakes devastated parts of Turkey and Syria, reducing many buildings to rubble.
Foreign Secretary James Cleverly said the impact of the quakes was “on a scale we haven’t seen for some time”.
More than 10,000 people are thought to have been injured.
No Britons were reported dead in the disaster, Mr Cleverly said.
The British rescue team “should be on the ground soon to give the Turkish authorities the help they need to try to save as many people as possible”, he said.
The UK is also sending specialist equipment, four specially trained dogs and a team of emergency medical practitioners in what Downing Street said was “significantly the initial response”.
Said No. 10 that the government was looking at ways in which it could support humanitarian action in north-west Syria, and that its first approach would be to work through the United Nations (UN).
Turkey’s disaster agency said more than 1,500 people died there, while an estimated 810 people died in Syria.
Those numbers are expected to rise further as rescuers plow through mountains of rubble in freezing, snowy weather.
The chairman of the Turkish Association of Britain said he had been “inundated” with calls from people worried about relatives.
Attila Ustun described it as a “heartbreaking” day for Turks everywhere and said there was a “very strong connection” between the Turkish communities in east and north London and the area where the quake struck.
He continued: “Some of them were born in those cities and towns that are now disaster zones.”
Mr Ustun said people from Turkish backgrounds were reaching out after the deaths of members of learning families, including “one gentleman in Bedfordshire who lost three of his uncles in one property”.
He said: “I’m overwhelmed, I had one woman in London crying her eyes out and saying that half her village is now rubble.
“People are calling me asking what they can do to help.”
The British Turkish Association is accepting donations, particularly of winter clothing, at various points across the UK.
Countries around the world have pledged or offered support for operations in southeastern Turkey and northern Syria following the disaster.
Other charities are also launching appeals, including the British Red Cross.
The chief executive, Mike Adamson, said the scale of the devastation caused by this earthquake was “shocking” with homes, hospitals and roads destroyed across the region.
“The priority right now is rescuing people from the rubble and Red Cross Red Crescent teams are on the ground in Syria and Turkey providing urgent support during these critical hours.”