The High Court on Monday rejected a bid by former media tycoon Jimmy Lai to bring a halt to his national security trial.

A panel of three judges dismissed Lai's claim that the way national security judges were appointed to hear his case lacked transparency and public accountability and would lead people to think he wouldn't get a fair trial.

The panel said all judicial officers are recommended by the Judicial Officers Recommendation Commission, an independent body, before they can be appointed by the chief executive.

"We do not agree that the CE is given a complete free rein in the matter," the panel said in a judgement.

It added that the assignment of cases is a matter wholly for the judiciary, and judges are subject to the Guide to Judicial Conduct.

"In our judgement, all the 'strands' put forward on behalf of [Lai] ... are insufficient to cause a fair and informed observer, having considered the facts, to conclude that there is a real possibility that any judge designated under [National Security Law Article] 44 would be biased, actually or apparently, against [him]."

Lai, who founded the now-defunct Apple Daily, is accused of colluding with foreign forces and conspiracy to print seditious publications.

He is due to face trial without a jury in September.