A federal judge has ordered former US president Donald Trump and his lawyers to pay more than $US937,000 ($1.4 million) in sanctions for suing former secretary of state Hillary Clinton over claims the 2016 presidential election was rigged.

US District Judge John Middlebrooks, who threw out Mr Trump’s lawsuit in September, said the sanctions were warranted because the former president had exhibited a pattern of misusing the courts to further his political agenda.

“This case should never have been brought. Its inadequacy as a legal claim was evident from the start. No reasonable lawyer would have filed it. Intended for a political purpose, none of the counts of the amended complaint stated a cognisable legal claim,” Judge Middlebrooks wrote in the 45-page written ruling handed down on Thursday.

He called Mr Trump “a prolific and sophisticated litigant who is repeatedly using the courts to seek revenge on political adversaries”.

Representatives for Mr Trump and his lead lawyer in the case, Alina Habba, could not be reached for comment.

Mr Trump sued Ms Clinton, the 2016 Democratic presidential nominee, claiming that she and other Democrats sought to rig that election by falsely accusing his campaign of links to Russia.

Judge Middlebrooks, who was appointed to the bench by president Bill Clinton in 1997, dismissed the case in September, calling the lawsuit “a two-hundred-page political manifesto outlining his grievances against those that have opposed him”.

Mr Trump, a Republican, sought re-election in 2020 but was defeated by Democrat Joe Biden, after which he repeatedly made false claims blaming widespead voting fraud for his loss.

He has launched a run for the 2024 presidential election, setting up a potential rematch against President Biden.

– AAP