French President Emmanuel Macron will be in Mayotte on Thursday, his office said, as officials warned the death toll from the most destructive cyclone in living memory could reach hundreds - possibly thousands.

France has declared "exceptional natural disaster" measures for Mayotte as authorities grapple with the full scale of the devastation wrought by Cyclone Chido on the Indian Ocean archipelago, racing against time to search for survivors and supply aid.

The "exceptional" measures, announced by French overseas minister Francois-Noel Buffet on social media platform X, will ensure "faster and more effective management of the crisis".

Rescuers raced on Wednesday to find survivors in the ruins of shanty towns while also unblocking roads and clearing rubble.

Bulldozers were clearing the heliport of the island's only hospital, as residents were busy repairing their metal-sheet huts.

Located near Madagascar off the coast of southeastern Africa, Mayotte is France's poorest region.

A preliminary toll from France's interior ministry shows that 31 people have been confirmed killed, 45 seriously wounded and 1,373 suffering lighter injuries.

But officials say the toll could rise exponentially. (AFP)