A federal judge has thrown out US President Donald Trump's defamation lawsuit against the New York Times over its content, calling it a "decidedly improper and impermissible" effort to attack his adversaries.

US District Judge Steven Merryday said Trump in his $US15 billion ($A23 billion) lawsuit violated a federal civil procedure rule by failing to offer a short and plain statement of why he should prevail over the NYT, four of its reporters and the publisher Penguin Random House.

He faulted the president for instead packing his 85-page complaint with unnecessary statements lauding his successes and "singular brilliance," attacking critics and even defending his father.

"A complaint is not a public forum for vituperation and invective - not a protected platform to rage against an adver

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