Sixty eight people were killed in the tropical storm that battered Madagascar over a week ago, according to new figures released Tuesday ahead of a national day of mourning.

"The flag is to be at half-mast on Wednesday.... All festive activities are suspended," the government said.

The hardest hit area of the Indian Ocean island saw 25 deaths, with the majority killed by landslides unleashed by the tropical storm known as Chedza on January 16 and 17.

Three-quarters of the island was impacted by the storm, which dumped heavy rains and prompted major flooding in low-lying areas.

A new storm named Dimanondra formed east of Madagascar on Tuesday, but it remained some 3,000 kilometres (over 1,860 miles) away, according to the national meteorological service.