The British Retail Consortium said that in the first days after September 11, retail sales were down by between 20 per cent and 30 per cent. That continued through the weekend and up to the start of last week.

"There was a definite temporary blip which we are still probably in," said the consortium, which had predicted depressed sales for up to two weeks. "But that period of uncertainty is starting to come to an end."

The consortium said the attention of retailers would now switch to the wider economic picture. Consumer confidence remained buoyant ahead of the attacks and stores groups would be watching for any early signs of a change in sentiment.

The first official figures to show the impact of the events in the US on the UK high street will come on October 8 when the consortium publishes it retail sales data.

FootFall, the organisation which tracks shopper numbers in more than 50 shopping centres in the UK, confirmed that customer numbers were picking up - but said they remained depressed.

The group, which reported a 10.6 per cent week-on-week drop in footfall on the day after the attacks, said that by Wednesday of last week, there were 7.7 per cent more shoppers back: "That shows that people are returning, but shopping centres are still in negative territory."