UPDATE 1-U.S. looking into hack attacks in wake of WikiLeaks

(Adds further Holder comment, background)

WASHINGTON Dec 9 (Reuters) - U.S. authorities are looking into cyber-attacks on companies like Amazon.com (AMZN.O) and others targeted by hackers backing WikiLeaks after it published classified U.S. communications, Attorney General Eric Holder said on Thursday

"We are aware of the incidents ... and I'll simply say we're looking into them," Holder told reporters after meeting European Union officials on a range of issues including terrorism, airline security, cyber-security and privacy.

The review comes after credit card giants MasterCard and Visa, Amazon and PayPal faced cyber attacks this week from supporters of WikiLeaks and the website's founder Julian Assange.

Amazon, which is a major Internet retailer and also provides web-hosting services, last week cut off hosting services for WikiLeaks' website after determining that it did not own the material it was publishing.

That provoked a backlash from WikiLeaks' supporters, some of whom launched cyber attacks.

Holder again condemned WikiLeaks and said that the Justice Department's investigation into the release of hundreds of classified U.S. diplomatic dispatches was continuing. He declined to provide additional details.

(Reporting by Jeremy Pelofsky; Editing by Will Dunham)