Ocado claims Tesco's negative advertising campaign over the price-match battle between the two retailers has backfired, as Ocado's sales shot up.

"On the day Tesco placed ads rubbishing us, we had our record number of orders on a Sunday," said Ocado chief executive Tim Steiner. "Registrations were up 8.5% on the week before and we had a significant increase in the number of people buying multiples, ie taking advantage of great prices on items and buying several at a time."

The battle broke out after Ocado said it would price-match Tesco on brands. It ran a national press campaign to promote the move, which Tesco countered with its own ads, claiming Ocado was misleading customers.

Tesco slashed its prices on brands in the first week of Ocado's new deal, forcing the online retailer into another round of cuts. "If you're going to claim to say you will price-match somebody, you do the legwork and make sure you're checking the prices and moving them up and down as necessary," Tesco said at the time.

Steiner insisted Ocado's commitment was genuine and permanent, and it would regularly check and match prices, even if Tesco continued to cut its prices.

Online specialist Ocado now flags up on its website in red which items are the same price as Tesco and has even changed its strapline to 'Tesco prices. Waitrose quality. Ocado delivery'.

Steiner said the publicity had led to "a 20% increase in browsing traffic and a huge increase in demand for delivery slots".

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