A “killer” shrimp has invaded UK waters and is feeding on native fish and insect larvae, North West water company United Utilities has warned.

Dubbed the “killer shrimp” by biologists for its appetite, it often kills its prey and leaves it uneaten.

The predator also alters the ecology of habitats it invades.

United Utilities says a new fishing craze from the US is behind the spread.

The craze has seen anglers use “floating tubes” - large inflatable tyres - to fish on water.

The tubes, which are easily transported, are thought to be helping the species spread by transferring eggs between rivers and other watercourses such as reservoirs.

United Utilities has confirmed it has banned the use of floating tubes at all its recreational reservoirs across the North West.

Originally from a region between the Black Sea and the Caspian Sea, the shrimp has spread across most of Western Europe in the past 10 years.

They can be as small as 3mm but may grow up to 30mm long, making it much larger than native freshwater shrimp.

Bosses at the company are working closely with the Environment Agency, county councils and fishery clubs to safeguard its waters.

Bryan Homan, water catchment operations manager, said: “Despite their fearsome name, the shrimp are not a threat to people.

"But the damage they could cause to our environment here in the North West is very real.”

An Environment Agency spokesman said: “It poses a serious threat to native wildlife in our rivers, lakes and streams and right now the priority is to establish how widespread the shrimp is and contain it through effective biosecurity measures.”