The public is today urged to become the eyes of a major campaign to control invasive species threatening the fragile ecosystem of the Broads.

People are being asked to report sightings of 'Norfolk's Most Wanted' – the most troublesome non-native plants and animals – on a special website.

And the message from Broads conservationists is not to spread invasive species by dumping garden waste or moving frog spawn along with plant material from their garden pond to a natural site.

Incredibly, many invasive plants are still openly available to gardeners and one recent report named 92 non-native species sold by garden centres and pond specialists that were in danger of spreading into the wild.

The latest menace is Himalayan Balsam (AKA Pink Peril), the rampant spread of which has alarmed the Broads Authority.

A massive effort is to be launched to eradicate the plant which is taking over along the Yare and Bure valleys.

The Broads Authority's senior ecologist, Andrea Kelly, said: 'In the Broads, costs seem to be working out at over �350,000 per year from the public purse to attempt to control non-natives.

'The costs would be considerably higher if we did not act quickly.'

The Norfolk Non-Native Species Initiative, led by Norfolk County Council, has submitted a bid to the EU Intereg fund for about �1.3m.

Ms Kelly said: 'The lakes and river are very vulnerable to invasion and that is why we are asking the public to get familiar with these species and let us know if they see them.

'The folk out walking dogs and cruising on their boats are our eyes and ears.'