The Electronic Privacy Information Center (Epic) and Junkbusters both said they would walk out of Amazon's affiliate programme, because of what they believe are unacceptable terms laid out in the bookseller's latest privacy terms.
Amazon's policy details what personal information the company gathers, why it is collected and how it is used. There are also details on how customers can protect themselves against unauthorised access to their passwords and computers.
The changes affect customers of Amazon's US site. The company's international sites in the UK, Germany and France control their own respective privacy policies.
In an open letter to Amazon chief executive Jeff Bezos, Junkbusters' president Jason Catlett said the revised terms are "unacceptably burdensome" to consumers, because the retailer has removed the option for them to send letters to [email protected], requesting that personal information is never sold.
An Amazon spokesman confirmed that the option to send letters has been deleted, but argued that the latest policy is more restrictive to the retailer.
He said the policy now states that the company will not sell, rent or lease customer information, and is more precise in detailing when data would be released to third parties. For example, Amazon has confirmed that it will sell customer information in the "unlikely event" that the company is acquired.
"If information is shared with a third party, customers will receive notification," said the spokesman. "We've eliminated the uncertainty and extended the 'never' option to everyone."
However, Epic believes that the latest assurances are inadequate. In a letter to Epic subscribers, executive director Marc Rotenberg said: "Amazon announced that it could no longer guarantee that it would not disclose customer information to third parties.
"Because of this decision, and in the absence of legal or technical means to assure privacy for Amazon customers, we have decided that we can no longer continue our relationship with Amazon."
The two organisations are members of Amazon's 500,000-strong affiliate programme, whereby Amazon provides links to their websites and is paid commission for any purchases as a result of click throughs.
Amazon declined to discuss whether it has received similar complaints from other partners.
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