The major supermarkets have agreed to offer online customers clearer pricing information following a long-running investigation by the OFT.
The OFT said Asda, Sainsbury, Tesco and Waitrose did not make it sufficiently clear on their web sites that the advertised prices were in-store prices which could change between the dates of order and delivery.
Now these four, along with online specialist Ocado, have vowed to provide greater transparency about their online shopping, with up-front information on guide prices and assurances that special offer prices quoted online are treated as firm prices for orders.
John Fingleton, OFT chief executive, said: "We welcome the improvements."
The OFT launched its inquiry last January following press criticism of supermarket internet offers and shopper complaints.