"For sale" signs will only be allowed if they fit in with the area

The boards will not be allowed in some streets and squares, such as in the Brunswick and Adelaide areas, unless they fit in with the conservation area.

The restrictions were brought in by the council after concerns about how signs were harming the appearance of the "finest formal squares and terraces".

Failure to comply with the regulations could result in a �2,500 fine.

'Unsightly clutter'

Councillor Gill Mitchell, from the environment committee, said: "We are concerned about the unsightly clutter seen against these magnificent buildings, many of which are Grade I or II listed.

"The council has worked hard to secure the necessary legal agreement and now we can go ahead and improve the appearance or our historic squares and crescents."

Many of the buildings in the streets concerned were houses of multiple occupation and could often have two or three boards at a time outside, the council said.

The authority said it had consulted with residents and estate agents and had received backing for the scheme.

Paul Bonnett, from Brighton and Hove Estate Agents' Association, said: "We are keen that local estate agents abide by the planning regulations and local agreements on avoiding the use of boards in historic areas."

The areas to be protected by the regulations include Adelaide Crescent; Palmeira Square; Brunswick Place; Brunswick Square; Brunswick Terrace; Arundel Terrace; Chichester Terrace; Lewes Crescent; Sussex Square; Montpelier Crescent; and Vernon Terrace.

The regulations will be in force for five years.