RESIDENTS of Dorset are being asked to keep watch for any unusual frogs and terrapins after recent 'alien' frog sightings in Bridport.

Conservationists are trying to gauge the number and location of non-native species to prevents them from wiping out the existing eco-system.

The amphibian and reptile conservation charity The Herpetological Conservation Trust is trying to identify the scale of the problem in an Alien Encounters survey.

Research and monitoring officer Dr Chris Gleed-Owen warned that alien encounters of amphibian and reptile species were becoming increasingly common in the South of England.

He said that there have been sightings of an alien frog, the marsh frog, in the Bridport area.

He added: "You would know if you had a marsh frog living near you as their calling noise at night is extremely noisy and could keep you awake."

It is illegal to release any non-native animals into the wild in England and some of the red-eared terrapins found now are a result of unwanted pets after the 'Teenage Mutant Ninja Turtles' film came out in 1990.

Dr Gleed-Owen said: "Most are unwanted pets and accidental introductions. There are around a dozen here already and some could cause problems."

Global warming is likely to increase the number of non-native species in the United Kingdom.

To contact the Herpetological Conservation Trust with any sightings visit www.alienencounters.org.uk