The Preston Tithebarn Partnership has announced that once the £700m transformation is completed in 2014 the city will be patrolled by guards round the clock.

This move to ensure the city centre is a safe environment has prompted concerns that developer Grosvenor could apply to have the public right of way scrapped, meaning access to streets could be barred if it wished.

In Liverpool, where Grosvenor is close to completing its £1bn Liverpool One redevelopment, the public's rights of way on some streets is to be scrapped under 'public realm agreements'.

The developer could ask for similar agreements on the land it has been given by Preston Council on a 250-year lease.

Donald Lee, of the North West branch of the Open Spaces Society, said that legal rights to walk down 33 streets in Liverpool had been replaced by "grace-and-favour access" – and he added Preston could suffer the same.

He said: "It is a cancer that is growing all over the place. Liverpool is just the latest in a long line of these kind of developments which have had these measures."

The society has unsuccessfully challenged the moves at public inquiries into developments in Liverpool and Wigan in recent years.

Mr Lee said: "We will give our two penn'orth if there is an inquiry in Preston."

In Liverpool, Grosvenor project director Rod Holmes has said the firm's vision for the 43-acre site in the city centre was aimed at "refinding" the city's streets.

He vowed there would be no gates in any part of its development and that people would have 24-hour access to all parts of the scheme. It is unclear whether there will be a similar scheme in Preston.

A spokesman for the Preston Tithebarn Partnership (PTP) said: "The Tithebarn scheme is designed around a series of streets and open spaces that form a natural extension to the city centre.

"It will benefit from round-the-clock security to ensure that it remains a safe and attractive place for shoppers, residents and other users of the city centre.

"While the scheme will be owned and managed privately, the streets and spaces will be open to the public 24 hours a day."

The idea of round-the-clock security has raised fears among business leaders that it could have a devastating impact on the rest of the city.

Nicholas Watson, chief executive of Preston's Chamber of Trade, said: "It is going to be very difficult for the police to be able to match that bar.

"If the security is going to be that intense, hopefully in a way it will encourage people to come into the city but I don't believe it will bode well for the existing shopping area."

Frank McKenna, chairman of lobby group Downtown Preston in Business, said: "Once you get a situation where one part of the city is fully secure then the inevitable consequence is it potentially has a detrimental effect on the rest of the city – why would people step out of this comfort zone?"

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