The Prime Minister has confirmed that British nationals are among those caught up in the aftermath of a huge blast in the Lebanese capital Beirut.
Boris Johnson said the Government is "ready to provide support in any way we can", and Foreign Secretary Dominic Raab said the UK stands in solidarity with Lebanon.
In a tweet, Mr Johnson said: "The pictures and videos from Beirut tonight are shocking. All of my thoughts and prayers are with those caught up in this terrible incident.
"The UK is ready to provide support in any way we can, including to those British nationals affected."
Videos of a huge mushroom cloud rising above the Middle Eastern city were shared extensively on social media on Tuesday evening local time.
The Lebanese Red Cross has said there are hundreds of casualties and a number of fatalities, with the authorities in the country yet to announce the cause of the explosion.
In a tweet, Mr Raab said: "My thoughts and prayers are with those affected by the devastating explosion in #Beirut today.
"The UK stands in solidarity with the people of Lebanon and is ready to offer help and support, including to those British nationals impacted."
Labour leader Sir Keir Starmer said in a tweet: "The images of explosions in Beirut are deeply worrying. Our thoughts are with those affected, the emergency services and the people of Lebanon."
Former chancellor Sajid Javid tweeted to say his "thoughts and prayers" were with the people of Lebanon, while London mayor Sadiq Khan said the city stood with Beirut amid "truly horrifying images" emerging from Beirut.
Liberal Democrat acting leader Sir Ed Davey said in a tweet there were "truly awful scenes and in a city that has already seen so much heartbreak".