A council blunder has sparked a bitter row between residents in a set of plush mews houses.

The planning battle, between Brighton and Hove City Council, residents and a wealthy retired jeweller, has transformed once-tranquil Marlborough Mews, off Western Road.

It started when Derek Edmonds, a retired Lanes jeweller, applied for planning permission in December to extend the kitchen of a property in the mews and convert the loft into a room.

The council mistakenly told him he did not need permission.

The house is owned by Geoffrey Whittaker and occupied by his mother. Her furniture was put in storage, the trio went to Spain and builders have now started work on the property by excavating the back garden.

However, the mostly elderly and retired residents of the mews - which are in a conservation area - are furious the building work is being allowed.

One resident has hired a solicitor to put pressure on the council to stop the builders.

The neighbours say the ground floor extension will take up most of the back garden and overlook adjoining properties, while the dormer windows of the loft conversion will destroy their privacy.

The council has now admitted it made a "mistake" and is deciding what to do.

Meanwhile, the builders say they will carry on working until they are told to stop.

David Sterling, of The Marlborough Mews Management Company which looks after the freeholds of the properties, said: "It is like something from MI5.

"When we got the enforcement officer down here he took one look and was horrified. He said, 'We've made a mistake,' and was out of here like a bat from hell.

"None of us are clear about what the council is now doing. The council has admitted it made a mistake and I don't understand why they don't now put a stop to the work. They seem to be running scared and are just allowing the building to continue."

A letter from council development control manager Maggie Brian to Mr Sterling said the council had made a mistake but it might not be able to take enforcement action.

She said: "The position is that, regrettably, advice was given to the effect that planning permission would not be required for the work proposed at the above property on the basis that it constituted 'permitted development'.

"However, this advice has now been found to be incorrect. The council's lawyers have advised that in this case the council may be legally stopped from taking further action, but I have nevertheless written to the owner and his agent to advise them that, in fact, a planning application should be submitted for the work."

The residents fear the council will not take action because it is worried about being sued.

Penny Bloor bought a house next door to where the building is taking place last week. She says she would have seriously considered pulling out of the sale if she had known.

She said: "I bought the house because it has a west-facing patio and I could sit there after work.

"It looks like the extension is going to block the sun as it will be two-and-a-half feet higher than my garden wall. It's going to affect my quality of life and I don't understand why the council said it didn't need planning permission."

Builder Mark Pulton, who is working on the extension, said: "We don't know whether we are stopping or starting. We are caught in the middle."

Solicitor Tony Allen, of DMH Planning, is acting on behalf of Mr Sterling.

He said the council was not constrained from taking action to stop the development because it gave the wrong planning advice to Mr Edmonds.

He said he would consider advising his client to go to judicial review unless the building work was stopped and the planning process restarted.

A spokeswoman for Brighton and Hove City Council said: "It would appear that Mr Edmonds was erroneously advised that he would not need planning permission for his proposed extension to a house in Marlborough Mews.

"The council is in contact with the solicitor acting for Mr Edmonds' neighbour, stating that the council is exploring the option of enforcement to stop the construction going ahead.

"Mr Edmonds is aware of the situation and the council is also in contact with his solicitor."

Mr Edmonds declined to comment.