British travellers have been urged to avoid the southern coast of Thailand as severe flooding claimed up to 21 lives in the region.

In particular, the Foreign Office is warning against “all but essential” travel to the islands of Koh Phangan and Koh Tao.

Storms and heavy rainfall have affected provinces including Krabi, Nakhon Sri Thammarat, Surat Thani, Phattalung, Chumphon, Trang and Satun.

Electricity and communications are currently disrupted across the region and there is a continued risk of mudslides and flash flooding in these areas.

Hundreds of tourists were trapped on the holiday island of Koh Samui, before being evacuated on a Thai aircraft carrier.

“There are roughly one million people affected in many provinces,” deputy prime minister Suthep Thaugsuban said.

“At first we thought the flood would last a day or two, but now it has already been one week.”

Air travel, road and rail links have been flooded and electricity cut to many areas.

A total of 80 districts in eight provinces have been declared disaster areas.