Businesses could be fined £2,500
Sandwich boards and other forms of mobile advertising are to be removed from parts of central London.
Westminster City Council has banned the boards claiming they clutter the streets and blight areas such as the West End and Covent Garden.
The council claims it is the first local authority to use powers under the London Local Authorities Act to get rid of this form of advertising.
On Monday, it begins a two-week crackdown in the West End.
Previously, all fixed advertisements, such as posters, were regulated but councils did not have control over mobile signs.
But the London Local Authorities Bill gives councils powers to regulate them.
SIX BANNED AREAS
Queensway / Westbourne Grove
Praed Street and around Paddington Station
Marylebone station and surrounding streets
Baker Street station and surrounding streets
West End - including Oxford Street, Regent Street, around Piccadilly Circus, Shaftesbury Avenue, Cranbourn Street, Leicester Square, Charing Cross Road and Covent Garden Piazza
Outside Victoria Station
Westminster has identified and written to shops and businesses using sandwich boards warning them about the change in legislation and the fact they will begin to enforce it.
City Inspectors and other officers will begin seizing boards they find in six specific areas in which they are now banned.
Both the business and individual holding the sign can be prosecuted but the council said it will target the company, for which the maximum fine is £2,500.
The council said the use of portable advertisements has become an increasing problem in Westminster with the number doubling to about 100 between 2005 to 2007.
Councillor Daniel Astaire said: "The West End is a world-class destination with 3.5 million visitors every week and these cheap and tatty signs have no part in its future.
"Visitors expect and enjoy the buzz of the busy streets around Oxford Street and Covent Garden but they do not want to fight their way past these signs cluttering up the pavement or see them disfiguring a beautiful conservation area."
The New West End Company, which represents businesses in the West End, and Heart of London Business Alliance, which covers businesses in Leicester Square, are supporting the initiative.