Rescuers in Indonesia are searching for at least 400 people who have been reported missing, many believed to be buried under landslides, after cyclonic rains caused disastrous flooding nearly a week ago.

The death toll on the island of Sumatra has risen to more than 440, the government says.

Aid has been sent into affected areas by air and by sea, but some villages have yet to receive anything, and there are reports of people stealing food and water to survive.

Some foreign aid has arrived, with Malaysia sending medical supplies to Aceh, one of the worst-hit provinces.

Millions have been affected by heavy rains across South-East Asia, including Thailand, Malaysia and the Philippines.

An exceptionally rare tropical storm, named Cyclone Senyar, caused catastrophic landslides and flooding in Indonesia, with homes swept away and thousands of buildings submerged.

People are missing in Aceh, North Sumatra and West Sumatra, the National Disaster Management Agency said.

There are two cities that require full attention due to being isolated, namely Central Tapanuli and Sibolga, agency head Suharyanto was quoted as saying by AFP news agency. Ships were expected in Sibolga on Monday, he added.

In Sungai Nyalo village, located about 100km from West Sumatra's capital Padang, floodwaters had mostly receded, leaving homes, vehicles and crops coated in thick grey mud.

The authorities had not yet begun clearing roads, residents said, and no outside assistance had arrived.

Resident Idris, 55, mentioned, Most villagers chose to stay; they didn't want to leave their houses behind. Reports of looting surfaced as some individuals broke into shops amidst the chaos, according to Police spokesperson Ferry Walintukan.

In another development, tech billionaire Elon Musk announced he would provide free Starlink services to support communications during the emergency.

Widespread devastation has impacted the region, with at least 170 dead in Thailand's floods and several casualties in Malaysia. In the Philippines, government corruption protests ensued after floods killed over 200 people this month, and Sri Lanka recorded at least 193 deaths from floods and mudslides as the weather disaster toll continues to rise.