The endangered white-clawed crayfish is to be released into a secret location within Kirklees to help prevent its possible extinction in the district.

The native freshwater species is threatened because of the introduction into Britain of the signal crayfish from North America.

It is being released as part of the Kirklees Biodiversity Action Plan.

Jeff Keenlyside, from Kirklees Council's environment unit, said: "The problem is that signal crayfish out-compete the native species. It can also carry a fungal disease fatal to the native species and, either way, populations of the white-clawed crayfish are being wiped out.

"Unfortunately, the signal crayfish is rapidly spreading into many water-courses and is now known to occur within Kirklees. Its spread is likely to continue and, ironically, this may be aided by improving water quality in our rivers."

The 40 individual crayfish to be released into the ponds have come from a captive-breeding programme run by Kirklees Friends of the Environment.

It is believed to be one of the few examples of the species being successfully bred and reared in captivity.

The ponds are on land owned by Kirklees Council, and the Environment Agency has undertaken water quality tests to ensure the site is suitable.