Flash floods swamped a border town as heavy rain hit Myanmar.

Footage shows soldiers building sandbag walls to shore against the raging waters in Chiang Rai province, northern Thailand, on April 29.

Muddy waters spilled into a market as the Sai River burst its banks - a perennial sight in the area as the monsoon season nears.

Local district chief Warayut Khomboon said downpours had battered neighbouring Myanmar, causing the river to swell.

The Highways Department had previously created a riverbank protection line to prevent flooding at the bridge. However, the project required removing old walls and sandbags, allowing floodwater to surge into both sides of the border.

The flash floods come as Thailand and neighbouring countries in Southeast Asia are approaching their annual monsoon rainy season which sees soaring temperatures followed by powerful rain storms.

However, the rudimentary infrastructure often struggles with the deluge, leading to widespread flash floods.