Levels of floating pennywort in the UK's rivers and lakes are at a record high with 50 tonnes of the invasive plant removed from the River Thames alone last year by the Environment Agency.

Fast-growing plants like floating pennywort can spread into the wild if they are not properly disposed of when removed from garden ponds ponds.

Biosecurity minister, Lord Gardiner said: "Invasive species pose a real threat to our country’s native plants and animals and cost the economy at least £1.8 billion a year. The 'Check, Clean, Dry' campaign is playing a key role in raising awareness of these threats – helping to prevent new arrivals and stopping the spread of invasive species already here. It is great to see the whole community of river users supporting this programme to protect the future of our precious native species."

Members of the public are being encouraged to report sightings of invasive plants through a 'PlantTracker' app and a campaign called 'Be Plant Wise' is advising gardeners on how to prevent the spread of invasive plants.

This week is 'Invasive Species Week', organised by the GB Non-Native Species Secretariat and Defra. It aims to get the public thinking about simple steps they can take to stop the spread of invasive species which threaten Britain’s plants and animals. For example, exotic pet owners are encouraged to never release pets, or let them escape, in the wild.