Reporting restrictions blanketing Hong Kong's largest national security prosecution were lifted on Thursday following an earlier a High Court ruling, shedding new light on pre-trial hearings that have dragged on for more than a year.

Beijing imposed a sweeping security law on Hong Kong after huge and sometimes violent democracy protests.

The law has criminalised most dissent and transformed the once outspoken city into something more closely resembling the authoritarian mainland.

The largest joint prosecution so far is of 47 leading democracy activists, most of whom have been held behind bars for over a year as prosecution and defence lawyers prepare for an eventual trial in what is new legal territory.

They are charged with "conspiracy to commit subversion" for organising an unofficial primary election.

Repeated requests by the defendants to lift reporting restrictions covering those hearings were denied by their trial judge Peter Law.

But earlier this month a more senior judge declared such requests must be granted, and on Thursday Law agreed to lift the restrictions.

During many of the pre-trial proceedings, which can now be reported for the first time, defendants have described feeling pressured by prosecutors to plead to what they believe are vague charges.

Defence lawyers have also argued that prosecutors have not properly detailed what the conspiracy is that their clients are alleged to have taken part in.

"The prosecution has been allowed to dance around and change and add (to the charges)," veteran barrister Gladys Li argued at one of the hearings.

"We will not be held at a gun point to offer a plea," she added.

The prosecution has denied being vague on the charges.

The 47 defendants are some of Hong Kong's best known dissidents, ranging from moderate reformists and former lawmakers to more radical China critics.

Some, like Joshua Wong and Benny Tai, are already serving sentences for protest-related convictions.

As the case has wound its way through the courts, most have opted to plead guilty -- a step that usually entitles them to a reduced sentence.

So far just 18 defendants have opted for a full trial.

It is still not clear when the trial will begin, and those in the dock face up to life in jail.

On Tuesday, AFP reported that Hong Kong's justice minister has ordered a no-jury trial for the 47 democracy defendants.

Instead it will be adjudicated by three handpicked national security judges.

China says the security law has reimposed stability after 2019's protests.

Critics say it has eviscerated Hong Kong's freedoms and brought Chinese mainland-style laws into a business hub renowned for its common law legal system.

Two senior British judges who used to sit occasionally on Hong Kong's top court stepped down earlier this year because of concerns over the security law.