London, UK - A UK court on Monday began hearing a lawsuit brought by Donald Trump over a lurid dossier compiled by a former British spy that contained unproven allegations against the US ex-president, who is open to giving evidence at the trial himself.

Trump is suing Christopher Steele and the company he founded, over the report which sparked a political firestorm when it was published just before his inauguration in January 2017.

The so-called Steele dossier contained unverified and controversial information about Trump and Russia that the former Republican leader has repeatedly denied.

It included allegations that Trump had been "compromised" by the Russian security service, FSB, and that Moscow had damning videotapes of Trump's sexual misbehavior during a 2013 trip to the Russian capital.

Donald Trump Trump calls on Biden to debate "tonight" despite trial: "I'll wait around!"

It also claimed that Russian President Vladimir Putin "supported and directed" an operation to "cultivate" Trump as a presidential candidate for "at least five years".

Trump denounced the dossier, which was leaked to Buzzfeed, as "fake". The New York Times has determined there was no corroborating evidence to support many of its claims. He is willing to provide "evidence at trial" to disprove the accusations.

Trump, currently the frontrunner to secure the Republican nomination for next year's White House race, filed a data protection claim against Steele and his Orbis Business Intelligence in Britain's high court in November last year.

It seeks unspecified compensation for "serious distress and reputational damage".

Monday's hearing is the first of two days of preliminary hearings in which Orbis will argue that the case be dismissed.

Donald Trump Trump claims there is more "hate" at Gaza student protests than Charlottesville

The dossier, produced before Trump's 2016 election win against Hillary Clinton, was commissioned by Democratic Party consultants.

Trump sued Clinton, Democratic Party leaders, and Steele over the dossier in March last year.

In November 2021, Igor Danchenko, a consultant and former researcher in Russian affairs at the Brookings Institution who was a key source for the dossier, was charged with lying to FBI investigators about his sources for the report.

Steele previously ran the Russia desk of the UK's Secret Intelligence Service known as MI6.