This is the dramatic moment volunteers saved two villagers who were washed away by a flash flood in northern Thailand.

The pair had tried to cross a waterlogged road across a river but were swept away by raging waters in Nan province on August 21.

Footage shows officers trying to throw a rope toward the locals being battered by the current. However, the two were carried off downstream.

They managed to grab onto a tree and were later helped onto a bridge by rescuers.

Authorities said heavy rain had been lashing Nan province in recent days. The downpours have flooded roads and spilled into farms and homes, forcing residents to leave for higher ground.

Nan governor Chainarong Wongyai said on August 22 that the rain had ceased, though 10 districts in the province remain heavily flooded.

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