A huge, mysterious 'dead zone' - 60,000 sq km devoid of oxygen and life - has been discovered in the Indian Ocean to the west of Australia.

Such zones have already been found off the coasts of North and South America, western Africa and the Arabian Sea.

But this is the first time one has been found encroaching into South-East Asia.

A study published in the science journal Nature Geoscience reveals a new 'dead zone' appears to be emerging in the Bay of Bengal, in waters extending from 100m to 400m in depth.

Dead zones are normally associated with a lack of oxygen and concentrations of microbes stripping the vital nutrient nitrogen out of the water.

In the case of the Bay of Bengal, no such nitrogen loss has yet been detecte
And traces of oxygen have been found - at levels 10,000 times lower than normal air-saturated surface waters.

While this is less than is needed to support most life, it also impedes nitrogen-harvesting microbes.