The crew of an oil tanker stranded near the coast of the Indian Ocean island of La Reunion after Cyclone Batsirai swept the region were rescued and brought ashore Friday, officials said.

"The perilous, very technical and unprecedented operation to rescue" the 11 Indian and Bangladeshi sailors on the Mauritian vessel TrestaStar was completed in "very unfavourable weather conditions", the French territory's prefecture said in a statement.

The cyclone is now heading away from the island, Emmanuel Cloppet, regional head of national weather agency Meteo-France, said Thursday, after it caused power cuts, felled trees and left several injured but with no major damage reported.

But "we are facing the worst weather conditions since the start of the episode", he warned, with winds of up to 150 kilometres (90 miles) an hour still battering the island.

The French minister in charge of overseas territories, Sebastien Lecornu, said the tanker was travelling empty and dismissed any risk of serious maritime pollution.

The French island was placed on red alert as the cyclone approached Wednesday, forcing its 860,000 inhabitants to barricade themselves indoors, with the eye of the storm passing nearly 200 kilometres (120 miles) from the coast early Thursday.

But that alert was lifted Friday at 9 am (0500 GMT), authorities said, while still expressing caution about the dangers posed by the cyclone.

The storm was then 250 kilometres (155 miles) northwest of the island, moving at a speed of 12 kilometres per hour.

The lifting of the alert "does not mean a return to normal", said the island's top official Jacques Billant, calling on residents to remain vigilant as several rivers remained at risk of flooding due to heavy rain.

"The consequences of the passage of the cyclone will still present dangers for the population."

He said travel was still discouraged as emergency services worked to clear roads, and restore electricity, phone networks and water supplies.

Access to the island's main coastal road, which connects the capital Saint-Denis to the island's other cities, remains cut off.

Earlier Billant had reported 12 people injured onshore by the storm, including 10 who had carbon monoxide poisoning, a firefighter who was electrocuted attending a roof fire and another who was injured after a fall from a roof.

Many across the island suffered water and power cuts.

After passing La Reunion, Batsirai is set to touch the east coast of Madagascar in southern Africa by the end of the week, Meteo-France forecast, potentially at the level of an "intense tropical cyclone" which could cause a "major" impact for the region.

Other tropical storms and torrential rains have wreaked havoc in southern Africa in recent days, leaving a trail of destruction in their wake.

Tropical Storm Ana claimed the lives of 86 people in Mozambique, Madagascar and Malawi last week.