WASHINGTON, May 12 (Reuters) - U.S. Republican presidential candidate Donald Trump said on Thursday that Amazon.com, the world's biggest online retailer, has "a huge antitrust problem."

In an interview on Fox News, Trump also said Amazon Chief Executive Jeff Bezos, who owns the Washington Post, is using the newspaper to influence politicians in Washington to help Amazon on taxes.

"This (Washington Post) is owned as a toy by Jeff Bezos, who controls Amazon. Amazon is getting away with murder tax-wise. He's using the Washington Post for power so that the politicians in Washington don't tax Amazon like they should be taxed," Trump said.

"He's using the Washington Post ... for political purposes to save Amazon in terms of taxes and in terms of antitrust," Trump said.

"He thinks I'll go after him for antitrust. Because he's got a huge antitrust problem because he's controlling so much, Amazon is controlling so much of what they are doing," Trump said.

Amazon did not immediately respond to a request for comment.

(Reporting by Eric Beech; Editng by Simon Cameron-Moore)