Knife gangs operating in Oxford Street are increasingly targeting small stores on the shopping thoroughfare. With security in larger stores becoming more sophisticated, the thieves see smaller shops, which often have only one or two assistants, as softer targets.

The gangs, which disappear into the crowds or jump on buses before police catch them, have boosted summer crime figures, up 17 per cent on last year. Pursuit is made harder because of roadworks on Oxford Street and Wigmore Street.

Police said that in less than an hour on one typical day they attended six robberies at small retail outlets. Three times more people per week are being arrested for shoplifting.

On August 25, three branches of the Sock Shop were robbed. Rhoda Persad, 21, an assistant at the firm's branch opposite Tottenham Court Road station, said: 'Every day we have three or four cases of shoplifting.

'The other day I tried to stop a man and ended up fighting with him at the door. I recovered pounds 152 worth of socks from one man the other day. I could not believe it. I thought he had one or two pairs, but I opened the bag and pulled out so many,' she said.

Sally Collinson, management co-ordinator for the Oxford Street Association, which represents 90 per cent of traders between Marble Arch and Tottenham Court Road and those in adjacent streets, said: 'This is one particular day and one particular gang. Oxford Street is a prime target. It is the most popular street in London.'

A security committee meets quarterly to discuss ways of dealing with crime, she said. One was to buy a mobile phone for Marylebone police station, so thefts could be reported instantly.

Stolen goods, known as 'shrinkage' in the trade, account for more than two

billion pounds a year in lost turnover and is said to be

growing at 15 per cent a year.