Rescue teams are searching for a British tourist who fell into the water while kayaking at a dam in Thailand.

Shanghaman Gowribalan, 24, was kayaking with his friend at the Rajjaprabha Dam in Surat Thani province at around 9 am on Sunday afternoon, February 11.

However, the Brit, reportedly fell into the deepest part of the reservoir, around 500 metres away from the Kraisorn Raft House, and could not swim to safety.

His frantic friend, also from the UK, rowed back to shore and pleaded with park authorities for help.

Police and rescue teams are now using sonar to search underwater for Shanghaman. They had still not found him on Monday afternoon, some 24 hours after he first went missing.

Worapote Lomlim, the local park director, said: 'Initial investigations suggest that the two tourists may have violated park regulations. In order to take a kayak out for paddling, you must register first to receive a paddle and life jacket from the staff.

'No registration was found. We believe the two tourists left early in the morning without wearing life jackets. Therefore, the head of the Khao Sok National Park will be investigating the facts.'

Worapote added that the area where Shanghaman had fallen was up to 50 metres deep (164ft) and the water was 'very cold'.

Scuba divers were deployed to search the waters, but the operation was temporarily suspended over safety concerns due to the dam's depth, cold temperature, and turbidity. The search and rescue was resumed today, February 12.

Boonruang Longlaluad, chief of the provincial disaster prevention and mitigation office, said the provincial governor has ordered experts from neighbouring teams to aid in the search.

More scuba divers from the island of Koh Tao and Chonburi province in the east of the country have arrived at the scene today.