Former US president Donald Trump has sued CNN for defamation, seeking $US475 million ($730 million) in punitive damages and claiming that the network had carried out a “campaign of libel and slander” against him.

Mr Trump claims in his lawsuit, filed on Monday in US District Court in Fort Lauderdale, Florida, that the network had used its influence as a leading news organisation to defeat him politically.

CNN declined to comment on the case.

Mr Trump, a Republican, claims in the 29-page lawsuit that CNN had a long track record of criticising him but had ramped up its attacks in recent months because the network feared that he would run again for president in 2024.

“As a part of its concerted effort to tilt the political balance to the left, CNN has tried to taint the Plaintiff with a series of ever-more scandalous, false, and defamatory labels of ‘racist,’ ‘Russian lackey,’ ‘insurrectionist,’ and ultimately ‘Hitler,'” the lawsuit claims.

The lawsuit lists several instances in which CNN appeared to compare Mr Trump to Hitler, including a January 2022 special report by host Fareed Zakaria that included footage of the German dictator.

Mr Trump, who in 2020 lost a re-election bid to Democrat Joe Biden, has not said whether he would seek re-election.

The lawsuit comes as the 76-year-old former president faces considerable legal woes, including a criminal investigation by the US Justice Department for retaining government records at his Mar-a-Lago estate in Florida after leaving office in January 2021.

Mr Trump was sued last month by New York state Attorney-General Leticia James, who has accused him of lying to banks and insurers over the value of his assets.

And a congressional committee is investigating the January 6, 2021, assault on the US Capitol by Trump supporters, focusing on his role in the attack.