The Guardian report says the banks have contacted US-owned Citibank to say they do not want to have anything to do with its service, launched today, which enables people to access all their online accounts through one Web site.

Citibank's My Accounts facility, which pulls together information about an individual's banking and share-dealing activities plus participation in reward programmes such as Air Miles, requires participants to disclose the Pin numbers and passwords for all the accounts they wish to include.

Citibank's Web site names Halifax and Abbey National among the financial institutions whose accounts can be aggregated. But the two said yesterday that they neither endorsed the service nor wished to participate, writes the paper.

Ambrose McGinn, e-commerce director at Abbey National, says: "If you give away Pins and passwords it will invalidate the terms and conditions of the accounts and leaves our customers wide open to potential malpractice."

Citibank claims to have taken advice from independent counsel to ensure the service is legal.