Flash floods killed at least 27 people and injured more than 20 at three waterfalls in the southern Thai province of Trang on Saturday as they celebrated the Thai New Year, disaster officials said.

Rescue teams were searching the area for about 30 people believed missing after the floods, triggered by heavy rains, swept over the waterfalls 10 km apart in the Bantad Hill Range, the Health Ministry's Relief Centre said.

Most of the victims were swimming below the Sai Roong (Rainbow) and Prai Sawan (Heavenly Forest) falls during a long weekend holiday for the new year Songkran festival and the search was difficult in the jungle area, police said.

Thirteen children, 10 boys and three girls, were among the dead at falls which are a popular destination for local families at holiday times.