'Suffocating' weeds to be removed

Floating pennywort, pictured in the Norfolk Broads, can kill river wildlife

A two-month clean-up operation has begun to remove huge weeds which are clogging up one of London's rivers.

The floating pennywort can grow up to 20cm a day and has to be pulled out of the River Wandle by hand as it does not respond to pesticides.

It suffocates aquatic life and the risk of flooding would increase if it were not taken away from the stretch between Sutton and Wandsworth.

The Environment Agency said the river had "suffered greatly" in recent years.

"Pennywort has been growing extremely quickly in the Wandle," biodiversity officer Joanna Heisse said.

It could stop light from getting into the water and reduce oxygen, she said, which would have "huge impacts" on fish, aquatic life and native plants.

The weed used to be found only in garden ponds but has been seen in waterways since the 1990s.

The £50,000 clean-up project is expected to last until the end of February.