Fourteen provinces in southern Thailand have been warned to prepare for potential flash floods, runoff, and prolonged flooding between Dec 3 to 5.

At least 13 people died and tens of thousands evacuated in one of the worst floods in decades to batter southern Thailand and northern Malaysia.

KUALA LUMPUR/BANGKOK (Reuters) -- Malaysia and Thailand are facing a second wave of heavy rain and potential flooding this week, authorities said on Monday, even as some displaced residents were able to return home and the worst floods in decades began receding in some areas.

There are worries in Malaysia and neighbouring Thailand that disastrous flooding could get worse as more rain comes.

At least 12 people have died and more than 600,000 households have been affected by the worst flooding in southern Thailand in decades, according to a government agency.

The death toll from the worst floods in decades in southern Thailand and northern Malaysia climbed to at least 12 on Saturday, authorities said, as tens of thousands of people were evacuated due to rising water levels in the past three days.