VANDALS are threatening a valuable wildlife habitat in Swindon by starting fires.

Large stretches of scrubland have been torched at the Seven Fields Nature Reserve in Penhill.

Around six areas at the north end of the reserve have been burned during the recent dry spell.

In the latest incident, an area of thick undergrowth the size of a tennis court went up in flames.

Conservationists say butterflies had laid eggs there and birds were nesting nearby. John Shailes, 69, of Emmanuel Close, Greenmeadow, was walking his dogs when the latest blaze started on an embankment about 2.15pm on Sunday.

He said: "The flames were about a metre high and there were clouds of smoke."

Firefighters were unable to get an engine into the reserve so four officers used beaters to contain the blaze.

The flames destroyed thick brambles which provided an important habitat for wildlife.

Mr Shailes saw three boys aged between eight and 11 crouching in the grass prior to the blaze.

Marilyn Beale, secretary of the Seven Fields Conservation Group, is furious at the spate of attacks, which started a month ago and have been getting worse.

In one incident a 50-metre long stretch of undergrowth was destroyed. She said: "The areas they have burned were fabulous wildlife habitats, especially for mammals.

"We have a variety of unusual butterflies which would have laid eggs in the long grass.

"We certainly can't look forward to many butterflies this year. We have had problems in the past, but this year it has been dreadful."

She is worried that the fires have disturbed nesting birds including wrens, robins, blue tits, chaffinches, magpies and goldfinches.

Residents say a small group of youths are responsible.

Andrew Hargreaves, station officer at Swindon Fire Station, said: "Apart from the environmental damage, the youngsters are putting themselves at considerable risk."

Sgt Graham Devine added that if anyone had any information they should pass it to him on 528111.

The nature reserve is owned by Swindon Council.