Travellers are being warned to avoid the Thai capital Bangkok after the city was hit by flooding.

Beside a wall of white sandbags that has become a front line in Thailand's battle to prevent an epic season of monsoon floods from reaching Bangkok, needlefish swim through knee-high water inside Sawat Taengon's home.

Soldiers, public works crews and volunteers raced to repair a key barrier protecting Bangkok’s northern suburbs from approaching waters today.

Thailand's prime minister is warning that rising floodwaters which have wreaked havoc across the nation are now threatening the capital, Bangkok.