Some of the UK's leading supermarkets are failing online shoppers with disabilities, according to charity AbilityNet.

AbilityNet carried out tests on supermarket websites to find out how easily accessible they were for users with disabilities such as visual impairment, dyslexia or a physical disability that makes mouse use difficult.

The organisation found that Sainsbury's, Asda, Somerfield and Morrisons failed to provide even basic levels of accessibility for disabled users.

But the supermarkets have denied the charge.

Morrisons said it is reviewing the content of its website "with the intention of launching a new integrated site in the near future which will be compliant with Disability Discrimination Act [DDA]."

Sainsbury's also said it is addressing accessibility issues and is working to improve its online service "for all disabled customers later this year".

Somerfield, which has no online shopping site, said: "Each Somerfield site complies with the World Wide Web Consortium's Web Accessibility Initiative A standard. We also worked with the Royal National Institute of the Blind and achieved the organisation's 'See It Right Accessibility' standard."

Only Tesco.com's alternative website, www.tesco.com/access, was classified by the charity as easily accessible.

"It is also popular with the non-disabled because they find it easier to use. Tesco is actually winding it in to its normal site. This is good for the disabled as well because nobody wants to feel 'ghettoised'," said a spokeswoman for AbilityNet.

Robin Christopherson, AbilityNet's web consultancy manager, said companies with websites that failed to be accessible to users with disabilities could fall foul of the DDA.

Companies were granted a five-year grace period by the Disability Rights Commission (DRC) to comply with the parts of the DDA that apply to the internet, which came into force in 1999.

"Individuals have already successfully won civil cases backed by specific charities for the disabled. These have been quietly settled out of court out of the public eye," Christopherson told vnunet.com.

"But the DRC publicly served notice in April that it would also take legal action if necessary."