A landmark national security trial for leading China critic Jimmy Lai opened in Hong Kong on Monday amid tight security, with the pro-democracy activist battling charges that he colluded with foreign forces, including the United States.

Queues formed outside the West Kowloon Law Court building the night before, with scores of police deployed. Hong Kong's security chief warned last week any attempts to disrupt proceedings would not be tolerated.

Lai, the founder of now-shuttered pro-democracy newspaper Apple Daily and one of the most prominent Hong Kong critics of China's Communist Party leadership, has faced a salvo of litigation under a China-imposed national security law that was enacted in response to a wave of pro-democracy protests in 2019.