One of the rarest species in the UK (Image by BCT/Hugh Clark)

The Forestry Commission hopes the new cave - or hibernaculum - on the edge of the Little Ouse River in Thetford Forest will give the rare barbastelle bat a quiet place to form a breeding colony.

Anne Embry, from the East Anglian District of the Forestry Commission, said: "We have 10 out of 14 British bat species in the Thetford Forest area.

"We know that six of these, including the barbastelle, hibernate underground.

"The natural place for these bats to hibernate would be a cave, but as there aren't many in this part of the world we are creating our own."

Barbastelle Bat Facts: There are only 5,000 barbastelle bats in the UK It is a woodland species It is normally found in Norfolk and the south west and mid west of England There are less than 30 hibernation sites in the UK

Nine years ago a hibernaculum was built in an old air raid shelter near the forest's visitor centre, but Forestry Commission staff believe it is too noisy for the barbastelle bats to settle and breed.

Ms Embry said: "The new site is about three miles away in a more remote area where the bats will be less disturbed."

The cave will be about 30 metres long and hidden by a mound of earth.

It will have a special bat grille fitted to keep out other animals.

Work on the cave is due to begin in February.