Keynote Systems has reported that Sainsbury's, which last month found that its e-commerce business was offline, is still suffering from availability issues.

In a note released today Keynote, which specialises in improving online performance, said that the supermarket's web site was down today between 12.45pm and 2.10pm. During this time, the firm explained, visitors could not access the site at all. In the previous outage the supermarket was forced to stop running its home delivery shopping business because it was unable to access its received orders.

"This is the second outage Sainsbury's has suffered in as many weeks, and while the retailer is reported to have lost nearly £1.5 million in sales last time, this is the least of its worries," said Martin Stern, regional manager for Europe at Keynote Systems. "Visitors to the site this afternoon are not going to be impressed when they can't order their shopping - one outage can be forgiven, but repeated problems will severely test the customer's loyalty."

Stern added that the timing was particularly bad as it happened at a time when people would be using the internet, a fact that could cost the company dearly.

"Friday lunchtime is likely to be a busy time for online shopping as workers around the country take the time to order in their food and drink for the weekend," continued Stern. "Missing out on this traffic is likely to have driven many online shoppers to competitive websites, and the danger is that they simply won't come back."