Indian authorities stepped up rescue and relief efforts in the state of Kerala on Monday, which has been ravaged by 40 percent higher-than-average rainfall in a monsoon season that claimed hundreds of lives. Officials in the southwestern state have called the rains the worst monsoon floods in a century.

Kerala was hit by extreme rainfall in May and then again this month, starting August 8. The severe floods swelled rivers and triggered landslides. Some 400 people have died, 220 in the last 12 days, and over a million have taken shelter in relief camps.

Officials said that 26 military helicopters and 1,200 large boats had been deployed for the rescue efforts. Relief assistance, including air-dropping food packets and water, is also underway.

Worries about disease

Light to moderate rain was expected on Monday across Kerala. The reduction in rainfall has helped rescue workers to set about trying to retrieve any bodies. At least 1,000 people are still missing from five villages around Chengannur, one of the worst-hit districts.

Indian health authorities said they were focusing on preventing the spread of disease. In particular, concerns remain over the lack of clean water.

"The biggest challenges immediately ahead are cleaning the flood-hit houses, rehabilitation, and prevention of water-borne diseases," said Mahesh P., a village-level officer from Rayamangalam, some 45 kilometers (28 miles) from Kerala's financial capital of Kochi.

Read more: Will extreme weather become even deadlier?

Flights allowed to land

The Indian military opened an air base to allow commercial flights to land in the state's busiest city of Kochi. This should also help with the flood-related operations, civil aviation minister Suresh Prabhu said.

Kochi's main airport has been closed since last week due to the severe flooding. Authorities said on Monday that they would proceed to open other airbases in the region to commercial traffic, to help meet the transportation needs of the area.

It is estimated that the floods have caused damage worth $3 billion (€2.6 billion), though the sum is likely to rise as authorities grapple with the full scope of the devastation.

Kerala state is home to 33 million people and is known for its tourist beaches and hill resorts.

jcg/msh (AFP, dpa, Reuters)

Each evening at 1830 UTC, DW's editors send out a selection of the day's hard news and quality feature journalism. You can sign up to receive it directly here.