US District Judge Barbara Rothstein in Seattle said Parler was unlikely to prove Amazon breached its contract or violated antitrust law by suspending service on January 10, and it was "not a close call".

She also forcefully rejected the suggestion that the public interest would be served by a preliminary injunction requiring Amazon Web Services to "host the kind of abusive, violent content at issue in this case, particularly in light of the recent riots at the U.S. Capitol".

"That event," she said, "was a tragic reminder that inflammatory rhetoric can - more swiftly and easily than many of us would have hoped - turn a lawful protest into a violent insurrection."

Parler was not immediately available for comment.

"We welcome the court's careful ruling," an Amazon spokeswoman said in a statement. "This was not a case about free speech. It was about a customer that consistently violated our terms of service."

Amazon said Parler ignored repeated warnings to effectively moderate the growth on its website of violent content, which included calls to assassinate prominent Democratic politicians, leading business executives and members of the media.

Researchers have said far-right groups at the Capitol had a vigorous online presence on platforms including Parler, where they spread violent rhetoric.

Parler said there was no evidence apart from anecdotes in the media that it had a role in inciting the riots, and it was unfair to deprive millions of law-abiding Americans a platform for free speech.

It also said Amazon had no right to threaten its "extinction" by pulling the plug, and had been motivated by "political animus" to benefit Twitter, a larger Amazon client that Parler said did not censor violent content targeting conservatives.

Rothstein rejected that argument, saying Parler had merely raised the "spectre of preferential treatment" for Twitter.

Many supporters of former US president Donald Trump favor Parler, which has claimed it had more than 12 million users.

Parler, which styles itself as a "free-speech" space, remains largely offline after being dropped by Amazon and the Apple and app stores. Those companies have cited Parler's poor record of policing violent content.

A static version of Parler's website recently returned, including a notice saying Parler was having technical difficulties, and a handful of posts from people such as Fox News hosts Sean Hannity and Mark Levin.

The site's internet protocol address is owned by DDos-Guard, which is controlled by two Russian men and provides protection from distributed denial-of-service attacks, according to infrastructure expert Ronald Guilmette.

Australian Associated Press