Plastic in the ocean is killing corals by drastically increasing their risk of becoming diseased, scientists have shown for the first time.

Researchers have calculated that there are now more than 11 billion items of plastic lodged in corals across the globe, raising the risk of deadly infections by up to 89 per cent.

Corals are already in danger from ocean acidification and warming seas which is causing mass bleaching events.

But for the first time, scientists have shown the impact of plastic. They believe the rubbish attracts microorganisms which can carry disease.

The team from James Cook University, Cornell University and the National Oceanic and Atmospheric Administration, surveyed more than 120,000 corals on 150,000 reefs from Indonesia, Australia, Myanmar and Thailand

Dr Joleah Lamb, from the ARC Centre of Excellence for Coral Reef Studies based at JCU, said: “We don't know the exact mechanisms, but plastics make ideal vessels for colonizing microscopic organisms that could trigger disease if they come into contact with corals," Dr Lamb said.

"For example, plastic items such as those commonly made of polypropylene, like bottle caps and toothbrushes, have been shown to become heavily inhabited by bacteria that are associated with a globally devastating group of coral diseases known as white syndromes."