Holidaymakers to Thailand have been warned that a thick haze blanketing Phuket poses a health risk.
The smog has also disrupted some flights, said the Tourism Authority of Thailand.
The UK Foreign Office said visitors should check with their airline if travelling through the region.
Anyone with respiratory problems has been urged to wear masks and local officials have advised people to stay indoors and not to take part in outdoor activities.
The haze, which has been caused by farmers lighting fires to clear agricultural land in Indonesia, has prompted hosptials to issue free face masks.
The average air pollution on Phuket over the last 24 hours has reached 136 micrograms per cubic meter, which is 16mg above the public safety limit.
A spokesman for the TAT in the UK said: ‘It is unusual for Phuket to be affected by these fires. Every year Thailand does experience a similar haze but normally much further south.
"Some flights have been delayed and tourists have been advised to take care, particularly those with children although that are very few UK families visiting Thailand at this time of year.
"We regret any disruption to UK tourist holidays but obviously this is out of our control. We hope, weather permitting the haze will clear in the next couple of days."
