British search and rescue specialists are travelling to Turkey to help search for survivors following the earthquake that has killed over 2,300 people.
A team of 76 rescuers is flying to Turkey on Monday evening.
Two 7.8 and 7.5 magnitude quakes have 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 that we have not seen for quite some time”.
More than 10,000 people are thought to have been injured.
No Britons had yet been reported dead in the disaster, said Mr Cleverly.
The British rescue team “should be on the ground shortly to give the Turkish authorities the help that they need to try to save as many lives as possible”, he said.
The UK is also sending specialist equipment, four specially trained dogs and a team of emergency medics in what Downing Street said was “very much the initial response”.
No 10 said the government was looking at ways it could support humanitarian action in northwest 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 had died there, while it is estimated that 810 people died in Syria.
Those numbers are still expected to rise as rescuers comb through mountains of rubble in freezing, snowy weather.
The chairman of the British Turkish Association said he had been “inundated” with calls from people worried about loved ones.
Attila Ustun described it as a “heartbreaking” day for Turks everywhere and said there was “a very large connection” between the Turkish communities in east and north London and the area where the quake struck.
He continued: “Some were born in those cities and towns that are now a disaster zone.”
Mr Ustun said people from Turkish backgrounds had been reaching out after learning family members had died, including “one gentleman in Bedfordshire who has lost three of his uncles in one property”.
He added: “I’ve been inundated, I had one lady in London crying her eyes out and saying that half of her village is now rubble.
“People are ringing me asking what they can do to help.”
The British Turkish Association is taking donations, particularly winter clothes, at different points across the UK.
Countries around the world have pledged or offered support for operations in southeast Turkey and northern Syria following the disaster.
Other charities are also launching appeals, including The British Red Cross.
Its chief executive, Mike Adamson, said it was “shocking” to see the scale of destruction caused by this earthquake 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.”