Close to 300 rare green turtles have been found dead on the beaches of southern Mexico, killed by a red tide of microalgae caused in part by climate change, authorities said.

The algae feeds tiny fish called salp that are toxic to turtles. It reached the shores of Oaxaca state a little over two weeks ago, the Federal Attorney's Office for Environmental Protection said on Thursday. A total of 292 turtles were found dead, it said, adding that 27 were saved and will be nursed back to health before being released back into the wild. The animals are endangered green turtles, which can grow up to 1.5 metres (5 feet) long. They nest all along the Mexican coast as well as elsewhere around the world, including off the shores of Hawaii and Australia.

Experts say the vast expanses of red algae are caused by several factors, including climate change.