A former leader of the now-defunct Hong Kong Alliance, Albert Ho, has pleaded guilty to a subversion charge in court.

The alliance and three of its former leaders – Ho, Chow Hang-tung and Lee Cheuk-yan – are the defendants in the High Court trial that opened on Thursday.

They were charged with incitement to subversion under the National Security Law.

The prosecution said calls by the alliance for "ending one-party rule" amounted to subverting state power.

Chow and Lee pleaded not guilty.

The trial is expected to last 75 days.