Hong Kong's first-ever trial under a United Nations anti-terrorism ordinance got underway at the High Court on Tuesday, over an alleged attempt to plant bombs and shoot police officers in 2019.

Cheung Chun-fu, Cheung Ming-yu, Yim Man-him, Christian Lee, Lai Chun-pong and Justin Hui deny "conspiracy to commit bombing of prescribed objects", while Lau Pui-ying has pleaded not guilty to a conspiracy charge relating to providing or collecting property to commit terrorist acts.

The prosecution told the court that the defendants had planned to plant two bombs during a rally marking International Human Rights Day in December 2019 – one on Hennessy Road in Wan Chai and the other around 100 metres away.

The first bomb was designed to make police move to where the second was planted, the prosecution said.

It said the second bomb was bigger, with a power radius of 400 metres, and it contained 150 iron nails which would have caused serious casualties and property damage had it been detonated.

The defendants also planned to shoot police officers, the court was told.

The prosecution told the nine-person jury that Cheung Ming-yu, Hui and Lai received military training in Taiwan in September 2019, and that the trio also went up a hill in Sai Kung to test their guns three weeks before the day of the planned attack, which police say they foiled.

The prosecution's witnesses for the trial include a co-defendant who pleaded guilty, Wong Chun-keung, who is said to have been the leader of the group behind the alleged bomb plot.

This is the first time that Hong Kong authorities have brought a prosecution using the anti-terrorism ordinance since it was enacted in July 2002.