DORSET's wildlife is facing an overseas invasion.

The Department for Environment, Food and Rural Affairs said research reveals everything from the American mink, which can prey on water voles and birds, to New Zealand pygmy weed can now be found in Dorset.

Other invaders include curly water weed and giant hogweed which can grow 16ft in four years, blot out competitors and whose sap can blister human skin.

More invaders include green sea fingers, the hottentot fig, the leathery sea squirt, the red-eared terrapin, the slipper limpet and the water fern which grows rapidly, forms dense mats and can swiftly choke lakes, ponds and slow-flowing rivers and streams.

DEFRA said the threat posed by non-native species had to be tackled and their spread controlled because of their impact on native wildlife and economic interests.

Educating people about the risks and how to avoid introducing such species was hailed as a key measure of DEFRA's strategy.

The organisation also wants a shared directory set up to show what invasive species are in which areas together with a rapid response framework for when invasive species are detected in Dorset for the first time.

DEFRA Minister Jeff Rooker, who launched the strategy, said: "The introduction of species over thousands of years has shaped British wildlife and the countryside that we love, but non-native species that are invasive can have a serious impact on native wildlife and are estimated to cost the British economy at least £2billion a year. With climate change the threat becomes greater. For the first time we now have a co-ordinated plan to tackle this."

A study in 2005 showed there were 2,721 non-native species in England, 1,798 were plants.

Environmental impacts of invasive non-native species include predation, competition and spread of disease while economic interests affected by these species include agriculture, forestry, fisheries and development industries.

Climate change is expected to enhance the ability of some non-native species to establish and thrive such as frost-intolerant plants surviving in milder winters.