The online retailer says the downtime was due to hardware failure, not hackers.
However, there is speculation on Twitter and in national press that Amazon has been attacked by freedom of speech campaigners after it stopped hosting WikiLeaks on its servers last week.
PayPal, Visa and Mastercard have all suffered similar attacks in recent days after withdrawing their services to the whistle blowing site.
Online activist group Anonymous, dubbed “hacktivists” are alleged to have caused a “distributed denial of services” (DDoS) attack to shut down Amazon’s website by spamming the site with data.
However, the group has since Tweeted a message denying any connection to the site shut-down.
The group, who tweet under the name AnonOps, said: “WE REPEAT: We can not attack Amazon.com. To some journalists: check your sources well please. #anonops #payback #Wikileaks #leakspin”
The failure, at around 8pm, affected the online retailer’s sites in the UK, Germany, France and Italy meaning consumers using the site for Christmas shopping were disrupted.
An earlier attempt to hack Amazon on Friday (10 December) failed.
Freedom of speech campaigners have called for consumers to boycott the online retailer in the run up to Christmas.
WikiLeaks has caused global controversy after making public confidential political documents. The US Government has said WikiLeaks is a security risk.