South Africa has turned two small islands in the southern Indian Ocean into its first offshore marine protected area, the environment ministry said Tuesday.

The protected status for the windswept Prince Edward islands, lying 1,777 kilometres (1,104 miles) from the South African mainland, aims in part to help toothfish populations recover.

Served in restaurants as Chilean sea bass, toothfish is known as "white gold" and has fallen prey to illegal fishing.

Beefed-up controls will include a ban on fishing within 12 nautical miles of the islands, and limited fishing in specified zones beyond that radius.

Environment Minister Edna Molewa hailed the move as "a significant contribution to the conservation of global biodiversity".

The islands in the southern Indian Ocean draw masses of breeding animals and birds including three types of seals, supporting 22 percent of the world's sub-Antarctic fur seals.

Four species of penguins, five species of albatross and 14 species of petrels also breed there. The islands support 44 percent of the Wandering Albatross.

The larger Marion Island covers 290 square kilometres (112 square miles) and has a base for environmental research and weather data collection.

The smaller Prince Edward Island is just 45 square kilometres (17 square miles).

The volcanic islands have an average annual temperature of five degrees Celsius (41 degrees Fahrenheit) and gale winds are common.

South African boats will be allowed to fish, with restrictions, for the Patagonian toothfish outside the new sanctuary in South African waters.