More than 2,000 shoppers queued early on Boxing Day to beat the rush to one of the first "New Year" sales.

Peter Larkin, the manager of Marks & Spencer at the Bluewater shopping centre, Kent, said some had been waiting two hours before the 1000 GMT opening.

Retailers across the country are hoping for a busy period after a lacklustre Christmas, blamed in part on the uncertain economic climate and the prospect of a war with Iraq.

Analysts suggest these sales could be the biggest for years, as shops off-load stock to customers who may have wised up to retailers' tactics - cannily waiting for the inevitable reductions.

Unless I get here early I may as well not bother Emma Smith Shopper

Mr Larkin said his two-floor store, one of 17 Marks & Spencer shops to start sales a day early, was packed with shoppers filling their trolleys with clothes, gifts and Christmas cards at 40% and 50% off.

Barry Stevenson, M&S retail director, added: "Our customers always welcome the opportunity to start their sale shopping early."

British Retail Consortium director David Smith said the best bargains were likely to be in fashion stores where items had been held back by a warmer than normal autumn.

A spokesman for dresswear shop Suits You in London's Oxford Street said it had been "packed out" since 50 customers waited for the doors to open at 1030 GMT.

"Shoppers are out in force and it will be a very good trading day," he said.

A lot of customers are being more careful whereas last year people were going mad Buchanan Galleries manager Hamish Millar

And there were 500 people outside the Next store at Manchester's Trafford Centre when it opened its doors to the first 300 at 0700 GMT.

First in the queue at the Next store was Emma Smith, 34, of Warrington, who arrived at 0450 GMT.

She said: "I have to get here early because clothes in the petite section sell out really fast.

"Unless I get here early I may as well not bother."

Staff at the Trafford Centre said the sales had started "extremely well" across the site.

But most of the other 280 shops in the centre will open on Friday, and managers expect hordes of early risers.

Fashion seems to be the prime target Eastgate Shopping Centre

There were similar scenes in Scotland.

Customers queued from 0500 GMT outside the Buchanan Galleries centre in Glasgow, according to manager Hamish Millar.

But although the centre was "very busy", Mr Millar added: "A lot of customers are being more careful whereas last year people were going mad."

Bosses at Buchanan Galleries expected about 100,000 shoppers to visit its 80 units by the end of the day.

People began queuing at 0600 GMT at Eastgate Shopping Centre in Inverness, the main centre for the Highlands and Islands.

By 0845 GMT the queue stretched the 130-metre length of the centre, according to a spokesman.

Retailers hope the sales will make up for a poor Christmas

"Fashion seems to be the prime target, whereas pre-Christmas purchases were gift goods - electronics or toys," he said.

But the spokesman added: "It was a quiet Christmas Eve and the only day our car park was not full, so I think people were saving themselves for today."

Alan Day, manager of Aberdeen's Trinity Centre, said he expected between 40,000 and 50,000 people on Boxing Day.

A lot of people were queuing outside Gyle Shopping Centre

Edinburgh's Gyle Shopping Centre was also very busy, according to a spokesman.

"A lot of people were queuing outside," he said.

Kate Mason, marketing manager of the Meadowhall shopping centre in Sheffield, said: "We expect customers to start arriving very early on the morning of the 27th to take full advantage of the sales."

Market analyst Footfall said the number of people at shopping centres was 7% lower than last year, for the last full week before Christmas.