Dozens of pupils were stranded in a school as heavy floods struck northern Thailand.

Video shows brown floodwater raging across the pavement near the Wiangkaen Wittayakhom School in Chiang Rai province on August 21.

A schoolbus caught in the gushing currents stalled and residents had to rescue the youngsters stuck inside.

Thanakrit Martphuthorn, a teacher at the school, said some 146 children were trapped as the deluge had rendered roads impassable.

He said: 'The school has provided them with food, and the deputy headmaster and teachers are taking care of them. The headmaster is stuck at the district office and has announced a one-day school break until the situation resolves.'

The Thai Meteorological Department on Wednesday forecasted widespread thunderstorms and heavy rain across northern Thailand, including Chiang Rai province.

Thailand and neighbouring countries in Southeast Asia are in their annual monsoon rainy season which sees soaring temperatures followed by powerful rain storms in the afternoon leading to widespread flash floods.