At least 10 people have died in flash floods triggered by torrential rain that battered Madagascar's capital Antananarivo overnight, an interior ministry official said Tuesday.

"The floods caused landslides and houses collapsed," Sonia Ray, spokeswoman for the ministry's disaster management office, told AFP.

Two people have been injured and more than 500 displaced from their homes, according to preliminary figures. 

Some 20 districts are on red alert, facing "imminent danger" of flooding.

Rescue teams have been mobilised to evacuate areas at risk, gymnasiums and other temporary shelters are being prepared for the homeless and the authorities are considering closing schools.

Madagascans shared pictures on social media of inundated streets and wooden huts swept away.

On Monday night, rainfall averaged 100 milimetres (four inches) per hour, Ray said.

The rainfall is expected to peak on Thursday but continue until the end of the month.

The country's wet-season woes are not yet over.

Weather forecaster Lovandrainy Ratovoharisoa said a cyclone was expected to strike the island's east coast at the end of the month. 

Two years ago heavy rainfall claimed the lives of 26 people dead, while 15 went missing and 90,000 were affected.