An empty Mauritian oil tanker with 11 crew members ran aground during a cyclone Thursday off the coast of the French Indian Ocean territory of La Reunion, local and mainland authorities said.

The French government's representative on the island tweeted that rescue workers were trying to reach the sailors on the TrestaStar tanker in "very difficult conditions" caused by tropical cyclone Batsirai.

"The sailors are unharmed and are still on the stranded ship," local authorities said, adding that 32 people — rescuers and medical staff — had been dispatched to help.

The French ministry in charge of overseas territories said the crew was made up of Indians and Bangladeshis.

The minister, Sebastien Lecornu, said earlier the tanker was travelling "empty", and dismissed "any risk of serious maritime pollution".

At least twelve people were injured on La Reunion earlier as the cyclone skirted the island.