A London agent has been fined and ordered to pay legal costs after a court ruled it had practiced fly-boarding.

Sovereign House Estates was prosecuted by the borough of Hackney, who took action after local people complained about boards being put up outside properties and left there for many months.

One resident reported the firm after finding a board had been erected outside her home without her permission.

The agency will now have to pay a £1,600 fine and £1,500 in legal costs, with Fiona Fletcher-Smith, the director of neighbourhoods and regeneration for Hackney Council, warning that other agents should be sure they are obeying the rules.

"If estate agents fail to clean up their acts, a bylaw will be introduced to put an end to all advertising boards on properties.

"Fly-boarding is ''environmental vandalism.'' The boards can damage property and are expensive to remove," she added.

Earlier this month, Hackney councillor Alan Laing told the Evening Standard the borough was investigating a number of agents for the offence and said that the council would be open to prosecuting those it felt were flouting regulations.