Severe floods caused by monsoon rains have killed more than 30 people and displaced tens of thousands in Malaysia and southern Thailand, with both countries preparing shelters and evacuation plans in anticipation of more heavy rain.

With tens of thousands already displaced, both countries set up shelters in anticipation of further downpours.

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.

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.

The floods also submerged large tracts of rice fields, causing millions of dollars in losses to farmers, officials said. The heavy downpour also damaged roads, houses and public facilities in Kelantan and other parts of Malaysia.