Tesco insist that their security is 'robust' and
"We know how important internet security is to customers and the measures we have are robust," the company said in a statement.
"We are never complacent and work continuously to give customers the confidence they can shop securely."
Troy Hunt, a security expert who revealed details of the flaws on his blog, told the BBC he believed the Tesco website was breaking some fundamental data storage rules.
Mr Hunt also criticised Tesco for not using HTTPS - Hypertext Transfer Protocol Secure - across its entire site.
