|Amazon has vast banks of computers that can be rented on a self-service basis to meet surges in traffic [AFP]
Amazon, the US internet company, has stopped allowing WikiLeaks to use its servers, forcing the whistle-blowing website to shift its services to Europe.
The move came after congressional staff had questioned Amazon about its relationship with the website, Joe Lieberman, an independent senator from Connecticut, said on Tuesday.
The site was unavailable for several hours before it moved back to its previous Swedish host, Bahnhof.
Just before Wikileaks released some 250,000 US diplomatic cables on Sunday, the website came under an internet-based attack that made it unavailable for hours at a time.
WikiLeaks reacted by moving the website from computers in Sweden to those of Amazon Web Services.
Amazon has vast banks of computers that can be rented on a self-service basis to meet surges in traffic.
But the move also exposed WikiLeaks to legal and political pressure.
"WikiLeaks servers at Amazon ousted. Free speech the land of the free--fine our $ are now spent to employ people in Europe," WikiLeaks said on Wednesday in a posting on the Twitter messaging service.
Amazon would not comment on its relationship with WikiLeaks.
"The company's decision to cut off WikiLeaks now is the right decision and should set the standard for other companies WikiLeaks is using to distribute its illegally seized material,'' Lieberman said in a statement.
He added that he would have further questions for Amazon about the affair.
Meanwhile, Barack Obama, the US president, has named an "anti-terrorism" expert to lead US efforts to mitigate the damage of the WikiLeaks breach and prevent future illegal data disclosures.
Russell Travers, deputy director of information sharing at the National Counter-Terrorism Centre, "will lead a comprehensive effort to identify and develop the structural reforms needed in light of the WikiLeaks breach," the White House said in a statement.
Washington has been in damage control mode ever since last weekend when WikiLeaks began publicly disclosing about 250,000 US diplomatic cables, many of which revealed embarrassing assessments of foreign leaders.
While the White House was seeking to downplay the impact of the security violations as late as Wednesday, the Travers appointment was among the clearest signs that the Obama administration was taking substantive steps to avoid a repeat.
Among his new duties, Travers will be advising national security staff on "corrective actions, mitigation measures, and policy recommendations related to the breach," said the White House.
He will also co-ordinate inter-agency discussions on developing actions "regarding technological and/or policy changes to limit the likelihood of such a leak reoccurring".
Travers has been tasked with collating the stream of "terrorism-related" information pouring into US agencies since the attacks of September 11, 2001.
The Washington Post described him as "the maintainer of the government database of terrorist entities and a co-ordinator of terrorism information-sharing initiatives".
The National Counter-Terrorism Centre where he works was among several agencies blamed for failing to uncover an alleged plot to blow up a US airliner on Christmas Day last year.