Hong Kong police arrested nine people, including six high school students, on suspicion of terrorism.
Members of the group are 15-39 years old.
Police said they had planned to rent a hotel room to build a bomb and attack city courts, transportation networks and streets.
The arrest occurs when Hong Kong leader Carrie Lam warns against “illegal thoughts” spreading throughout the city.
The group, held under national security law, has been used to shatter dissent after years of anti-democratization movements, primarily led by young activists.
Police said they had seized the highly explosive chemical triacetone tripeloxide (TATP) in a hotel room that was used as a laboratory for bomb-making equipment.
HK $ 600,000 ($ 77,000; £ 56,000) linked to the group was also tracked and frozen.
“We were planning to attack some of Hong Kong’s public facilities, including cross-harbor tunnels, railroads, and courtrooms, and even wanted to bomb a trash can on the street,” Lee Kwaiwa told reporters. Said. To maximize the damage to society. “
Shortly before the arrest was announced, Hong Kong Chief Executive Carrie Lam urged parents, teachers and religious leaders to monitor teenagers and report suspicious crimes.
She said at a weekly press conference that the government department should not allow what she called “illegal ideas” to spread throughout the education system.
She also praised the National Security Act imposed on the territory by Beijing last year.
“For a long time, citizens have been exposed to false ideas, such as achieving justice by illegal means,” Lam told reporters.
She also criticized those mourning the death of a man who stabbed and injured a police officer before taking his life on July 1.
The incident took place on the anniversary of the transfer of the former colony from Britain to Chinese rule and on the 100th anniversary of the founding of the Chinese Communist Party.
In the past, large-scale protests against Beijing’s growing influence were organized on anniversaries.
However, this year’s demonstrations were banned and all participants were sentenced to life imprisonment under the National Security Act.