Security outside West Kowloon Court was stepped up on Monday morning ahead of a high-profile national security trial of former media tycoon Jimmy Lai.

Lai, the founder of the now-defunct Apple Daily, is accused of colluding with foreign forces to endanger national security and conspiring to print seditious publications.

Dozens of police officers were seen patrolling around the area, while barriers were set up outside the court building. Observers and judicial officers were required to pass through X-ray scanners when entering.

The judiciary has set aside more than 300 seats for the public to attend the trial, which is expected to last 80 days.

Three national security judges Esther Toh, Susana D'Almada Remedios and Alex Lee will preside over the hearing.