Online giant Amazon UK was offline for half an hour during the peak Christmas shopping period last night amidst ongoing cyber threats by pro-Wikileaks saboteurs Anonymous.

Amazon’s UK website was down for about half an hour from 9.15 last night and its German, French, Austrian and Italian sites were also reported to have experienced problems.

The online retailer said the outage was caused by a “hardware failure” although a message posted on a Twitter account thought to be affiliated to Anonymous, suggested an attack had been launched. It said: “We can’t confirm anything because we’ll lose our accounts again. Be alert and you will realize.”

The online activist group has said it is targeting Amazon following the etailer’s withdrawal of hosting of the whistleblowing website. The so-called ‘hacktivists’ had threatened to attack Amazon’s website on Thursday but its defences proved impregnable.

Anonymous also reportedly brought down Mastercard’s website last week after the payments firm refused to process donations to the Wikileaks. Visa and Paypal have also been targeted.

Amazon said that all its servers are back up and running and normal service has been resumed.