A British river has the worst microplastic pollution in the world, researchers have found, with levels even greater than hugely built-up areas such as in South Korea and Hong Kong.

Geographers at The University of Manchester are calling for tighter regulations to prevent plastic entering waterways after finding ‘extraordinarily’ high concentrations in north west England.

The team examined river sediments from 40 sites across Greater Manchester including urban rivers and rural streams. They found microplastic everywhere even in the remote parts of Saddleworth Moor in the South Pennines.

But the River Tame at Denton was found to have the highest levels of microplastics recorded anywhere in the world, at 517,000 particles per m2. The level was far higher than at the Incheon-Kyeonggi beaches in South Korea or the Pearl River Estuary in Hong Kong.