People on Narrowboat holidays have been advised to keep an eye out for unusual shrimp in the UK's canals and rivers.

British Waterways made the call after the Environment Agency confirmed sightings of a so-called invasive killer shrimp for the first time in Cambridgeshire.

Experts do not believe the creatures will be present outside the Grafham Water reservoir where they were spotted, but the public are nevertheless being asked to keep an eye out.

Chris John, national ecologist at British Waterways, said: 'Invasive species are a real problem for the UK's waterways, they affect our native flora and fauna, damage our historic structures, divert resources and reduce our ability to keep the waterways safe and attractive.

'He added that appropriate action will be taken if the creatures are found to have infiltrated more waterways across the country than previously thought.

A recent study was launched into the colonisation of the Red Swamp Crayfish in the UK's inland waterway network.