Angry boat-owners are threatening to blockade Brighton Marina in protest at £50 million development plans.

Five new buildings proposed by Parkridge Developments would transform the harbour and members of Brighton Marina Yacht Club believe the original purpose of the marina, dating back to the Sixties, is being lost.

They are angry an estimated 90 per cent of visitors now use the marina for non-boating reasons.

Club chairman John Duffy has written to deputy prime minister John Prescott to argue against further commercial development at the site.

He said yacht-owners were already finding it difficult to find parking spaces and the problems would only intensify with new shops and homes.

Mr Duffy said: "Many boat-owners have become increasingly dissatisfied with the way they are treated and feel they are now second-class citizens within the marina.

"Some of the more militant berth-holders are talking of blockading the marina by both land and sea if the council and marina owners do not start to take some notice of those who should be the prime users of the marina."

Parkridge managing director Philip O'Callaghan argued that improving the overall look and facilities of the marina would benefit everyone.

He said: "Our plans will make this a more attractive place.

"A lot is being done to improve things for boat-owners. The whole marina is being dredged and Premier Marinas, the owners, have invested millions in recent years improving the pontoons."