Shoppers find Ocado the hardest of the grocery websites to use, new research has revealed.

The online-only grocery retailer scored well with customers on delivery and customer service but lagged behind its supermarket rivals on first impressions, search, ease of basket use and product information.

EDigital Research said the result was largely due to improvements in Tesco, Asda and Sains­bury's websites over the past year. Waitrose was the top-ranking grocer, with a score of 85.2%, followed by Sainsbury's on 84.9%.

"We take EDigital Research's findings firmly on board but know from our own customer feedback that it's not just delivery and customer service we're getting right but our web platform too," said Ocado PR manager Ben Lovett.

"We're planning further website enhancements for customers next year."