THE death toll from Thailand’s worst floods in half a century climbed past 500 yesterday, as advancing pools of polluted black water threatened Bangkok’s subway system and new evacuations were ordered in the sprawling capital.

The main river coursing through Thailand’s capital swelled to record highs today amid fears that flood defences could break and swamp the heart of the city.

Tens of thousands of Thais are fleeing flood-threatened Bangkok after as the city’s governor ordered official evacuations for the first time since the crisis began.

Flood waters have begun seeping into Bangkok’s outer districts, one day after the government opened key floodgates in a risky bid to let built-up water flow into the sea.