A check of 156 popular websites in the UK has suggested that 62 might not be in full compliance with consumer protection laws.
The UK Office of Fair Trade OFT found unreasonable restrictions on refunds as also compulsory charges being added with no prior notification at the online checkout.
The retailers have been asked to change their websites before Christmas.
In the sweep this year, which has been the biggest so far, 100 of the most-used online retailers in the UK, and the most popular clothing sites were found to be
wrongly telling their customers that returned goods must be in their original packaging or in their original condition.
According to the OFT this could be in breach of the right of the buyer to inspect or assess a product.
Around two-thirds of all the retailers checked did not provide an email contact address, as against a web contact, which was a breach of the e-commerce regulations.