BRAEHEAD shopping centre opened to the public yesterday - amid fears that retail turnover in nearby Paisley and Renfrew town centres will crash by up to 20%.

Even Glasgow city centre may not escape, with turnover expected to fall by 3%-5% as consumers flock to the latest out-of-town complex, Scotland's largest development of its kind.

The #285m, privately-funded development, has more than 100 quality shops plus leisure facilities within 20 minutes drive of 25% of the Scottish population. Almost 50% live within 45 minutes drive.

Already, it is valued at #486m: the most valuable individual commercial site in Scotland. With ample public transport links also provided, the impact on surrounding areas will be significant.

However, last night all the major centres affected by the massive centre, situated on the outskirts of Renfrew and Govan, put on brave, optimistic faces.

The official line is that Glasgow city centre sees Braehead as a challenge it will beat off, while Paisley and Renfrew regard it as a marketing tool which will boost their economies. Privately there are real concerns, with one former Strathclyde Regional Council official describing it as ''Scotland's worst-ever planning decision''.

Research suggests there will be a ''honeymoon period,'' followed by a settling down, and, finally - perhaps - spin-off growth. Indeed, Paisley may already have suffered the worst. During the long run-up to the opening, High Street retailers voted with their feet. Rental rates, once among the highest in Scotland, slumped.

But major new developments are under way, and Marks and Spencer - a lead anchor at Braehead - has pledged it will remain in Paisley town centre, where #11m is being spent on refurbishments and new property, including housing.

Professor Leigh Sparks, of Stirling University's retail studies department, suggested that Braehead's impact may prove positive to the wider area in the long term.

He cited research from similar developments in Newcastle, Sheffield, and Bristol to support that view, also backed yesterday by Braehead marketing manager Anne Ledgerwood. She argued it would add to shopping attractions within Greater Glasgow and the West of Scotland, and added: ''Similar fears emerged among traders before the MetroCentre opened in Newcastle. But, after a dip in sales, growth was recorded. They feed off each other.''

Braehead's manager, Capital Shopping Centres - whose portfolio includes MetroCentre and Lakeside in Essex - also rejected concerns. Managing director Douglas Leslie insisted: ''We are creating new opportunities for local businesses and a new workplace for the local community.''

Paisley Chamber of Commerce chief executive Liz Cameron was also upbeat, despite acknowledging that numerous shopkeepers in Paisley, Renfrew, and Johnstone have voiced fears that they might not survive. Ms Cameron believes that was a panic reaction, and claims Braehead is now perceived as an opportunity rather than a threat. She said: ''It would be foolish and dangerous to set out to compete with Braehead. Instead, the challenge is to make sure that Paisley and its attractions become part of its portfolio.''

Mr George Sneddon, new director of Glasgow's City Centre Partnership, said Braehead could take up to 5% of retailers' turnover. However, he was bullish: ''Brae-head means that everyone will have to be a bit sharper. It has nothing the city centre cannot provide, but we are not sitting back.''