Privacy International claims to have received a number of complaints from internet users over the past 12 months alleging that some companies have either disabled or obstructed the deletion of customer accounts.
Privacy International warned that this practice would breach the rights set out in the Data Protection Act.
"Our research established that the vast majority of users of these sites were unable to delete their accounts," said the privacy group.
"Some, such as eBay, require a process that involves intuition, good luck or dogged persistence. Others, such as Amazon and Friends Reunited, appear to have no facility whatever to delete accounts."
Privacy International believes this is important in ensuring best practice and legal compliance.
The organisation further alleged that the lack of account deletion and disclosure arrangements breaches key elements of the Data Protection Act.
"In our view it is in these companies' financial interests to hide the account deletion function, and thus they have acted in an entirely self-serving manner that denies millions of customers an important right," the organisation claimed.
Privacy International has lodged a complaint with the UK's Information Commissioner, requesting a formal investigation.
The test complaint has been directed at ebay.co.uk, which claims a user base of over 10 million UK consumers.
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