BRITAIN is about to be overrun by an invasion of killer crabs, North-East researchers are warning today.

Chinese mitten crabs - named because of the distinctive tufts of dark brown fur on their claws - are multiplying at an alarming rate along our coasts and rivers.

The exotic invaders, which were first brought to these shores last century in ships' ballast, could cause devastating environmental problems if their numbers are not controlled, say the authors of a Newcastle University report.

The study, published in the academic journal Biological Invasions, is calling for the crabs to be monitored and trapped before it is too late to control them.

The crustaceans are unwelcome because they feed on native British species, such as white-clawed crayfish and the fry and eggs of salmon, but also burrow up to 18 inch-long tunnels, which threaten to undermine riverbanks.

The university report examined the crabs' unstoppable march through Europe early in the 20th Century and its recent inroads into the UK and concluded that the spread was taking place at the same alarming rate.

Chinese mitten crabs can already be found on the Tyne, the Humber and the Thames, but the study concludes that they are spreading around the coastline at a rate of almost 450km a year and have the potential to establish themselves in all major UK estuaries within a few years.

The spread was most marked on the North-East coast, partly fuelled by falling levels of river pollution. Mitten crabs can live in fresh or salt water, but must migrate to the sea to breed.

Researcher Dr Matt Bentley, of Newcastle University's School of Marine Science and Technology, said: "This study demonstrates the importance of a monitoring programme for the mitten crab, even if its appearance is just a rare occurrence in an estuary.

"Records demonstrate the crab's ability to rapidly expand once the local population reaches a critical density or conditions become favourable.

"With most invasive species, such as the grey squirrel, the problem is not recognised until it is too late to do anything and you can not eliminate it without taking drastic environmental measures.