Officials estimate the damage runs into billions of dollars, a headache for the island nation just recovering from an economic crash.

Landslides and flooding across Indonesia, Sri Lanka and Thailand have killed more than 1,200 people in the past week, and 800 others are still missing, authorities said Tuesday.

"We are facing the largest and most challenging natural disaster in our history," Sri Lankan president Anura Kumara Dissanayake said in an address to the nation on Sunday. Businesses across the country have been reacting with compassion and alarm.

Indonesia and Sri Lanka hit hardest as climate change-boosted monsoon flooding wreaks havoc across Southeast Asian nations.

Sri Lankan authorities said they would need around US$7 billion to rebuild homes, industries and roads destroyed by Cyclone Ditwah.

Governments and aid agencies across Indonesia and Sri Lanka are rushing supplies to hundreds of thousands stranded after monsoon floods and cyclones killed more than 1,300 people in four countries.

Sri Lanka tourism players are rushing to restore normalcy across the country after Cyclone Dilwah’s impact last week. This task is particularly urgent, as November and December are peak months for inbound tourism.

Wassana Suthi spent last week trying to keep a nursing home running as the floodwaters rose around her in the southern Thai city of Hat Yai, cutting the home off from outside help, bar one helicopter dropping supplies on the roof.

Residents of Kithulbadde village in central Sri Lanka say they have been left in the lurch after last week's deadly cyclone and many are stuck in relief centres as damaged infrastructure has made them wary of returning home.