Brighton's most cosmopolitan shopping streets are being threatened by the creeping blight of middle-class blandness, traders have warned.

Shopkeepers and community leaders fear an invasion of mainstream cafs and expensive restaurants could spell the end for the bohemian North Laine quarter.

Gabrielle Villermet, of the North Laine Community Association, said: "North Road will soon become wall-to-wall restaurants from the restored Argus building to the bottom of the road.

"We are concerned that if the large chain cafes and shops move into North Laine, its unique mix and diversity will be lost and this will affect us all."

In a report to the association's annual meeting she added: "We are also concerned about the changes of use to residential property involving loss of small workshop space.

"While appreciating the need for more housing, we feel North Laine has now reached saturation point."

North Laine grew up in the 1830s and boasts some 300 shops selling everything from Fifties clothing and jewellery to Balinese furniture, pottery and vegetarian shoes.

But many traders feel its 37 cafes are ruining the ambience and attracting the wrong sort of shopper.

Amy Holton, 20, manager of alternative clothing store Spanki, in Sydney Street, said: "If it's not restaurants it's Costa Coffee or the kind of shops Brighton already has a million of.

"You see a lot of shops which have been there a long time closing down or changing into something we don't need.

"North Laine still has atmosphere but it is changing. It's not the same as it used to be.

"When I was younger it seemed to be really wacky but it has got a lot more mainstream."

Jo Nean, 23, of fancy dress store Revamp, in Sydney Street, added: "I wouldn't like to see a lot more restaurants.

"This should be more of a student arty area."

The North Lane Community Association's retiring chairman, Barry Leigh, said members were powerless to halt the rise in shop and house rents pricing young people out of the market in North Laine.

They had managed to have an effect on planning issues locally, however, such as over the Brighton station and central library sites.

Mr Leigh added: "On some issues, such as the proliferation of restaurants, the local authority would seem to be like a toothless tiger."

Brighton and Hove City Council has a policy of not having too many cafs next to each other in the city centre and takes enforcement action if cafs open without permission.