A crucial decision about whether a developer can build a 40-storey tower at Brighton Marina has been delayed.

Brighton and Hove City Councillors were last night asked whether a law banning tall buildings at the marina can be overturned.

The debate was postponed until next week because councillors said they did not have enough time to consider the latest legal advice.

Protesters, many of whom staged a demonstration outside the meeting, welcomed the adjournment, complaining that councillors were presented with complicated legal statements at the eleventh hour.

A report by a barrister had been sent out on Wednesday evening. Peter Martin, vice-chairman of Brighton Marina Residents' Association, said: "The way the council acted is a disgrace. It is right and proper that the council takes its time, irrespective of the legal advice it receives."

The 1968 Brighton Marina Act forbids buildings higher than the marina cliff. But a clause says this law is to protect the local authority, then Brighton Corporation, and does not apply if "otherwise agreed in writing between the company and the corporation".

Opponents argue this clause was intended to allow structures such as lamp-posts, guard rails or harbour lights but not large buildings.

Brunswick Developments wants to build 853 flats with car parks, a viewing gallery, crche, doctor's surgery and health facility. The tallest tower, dubbed the "Roaring Forties" would reach well above the height of the cliff.

The council's legal advisors have warned that if the council does refuse planning permission, it may fall foul of the High Court.

Council leader Simon Burgess said he believed no council should have the power to determine what its successors should be allowed to do into the future. He said: "This is one of the most important decisions to come before us for years."

He said the development would be a "striking, modern, iconic landmark with cutting-edge architecture".

Forty per cent of properties would be affordable.

In a speech before the debate Derek Granger, of the Kemp Town Society, said legislative changes must come from Parliament. He said Brighton had committed itself to a marina lower than cliff height when there was a referendum in the city about whether to allow a marina at all.

Alan McCarthy, chief executive of Brighton and Hove Council, said last night's decision was a delay but the advice from three separate sources was still the same.

He said: "Our own legal team had given advice and the developers had given legal advice they obtained from a QC who was external to them. I didn't think it was necessary to ask for independent legal advice.

"But councillors started expressing concerns about a week ago and asked for the independent legal advice and we immediately acted on it.

"We now have legal advice from three sources and they are all consistent. But councillors felt they needed more time to consider the advice being given and further opportunities to ask questions."

The council will debate the matter at Hove Town Hall next Thursday at 5pm.