UK travellers have been advised to avoid all but essential travel to Bangkok as tens of thousands of Thais have been ordered to evacuate the flood-threatened city.
The Foreign Office has changed its travel advice in response to the large volume of floodwater expected to hit the capital in the coming hours.
Heavy rainfall across the country has killed more than 350 people and caused flash floods, mudslides and widespread disruption.
Foreign Office Minister Jeremy Browne said: “Our thoughts continue to be with the people of Thailand at this difficult time and in the face of unprecedented flooding.
“However, as Prime Minister Yingluck Shinawatra has now said that waters will reach the capital, we have updated our travel advice to reflect the worsening situation.”
Satellite images of Bangkok showed a city almost completely surrounded by water.
The Government of Thailand ordered a public holiday from yesterday until Monday when tourist attractions were likely to be closed.
Travellers were advised to avoid the 26 provinces affected by flooding and UK nationals already in Thailand were urged to be cautious.