The police said on Tuesday that they had arrested two men after finding 23 kilogrammes of bomb-making chemicals, foiling a potential "bloody attack" around Lunar New Year.
The men, aged 62 and 42, were suspected of conspiracy to manufacture explosives, and possessing offensive weapons and ammunition without a licence.
The force said as well as the chemicals, which included potassium nitrate and suspected magnesium, they seized batteries, firecrackers, remote controls for fireworks, gas masks, and a USB cable.
Ho Chun-tung, a senior superintendent of the Organised Crime and Triad Bureau, said the materials could have been made into bombs that would have inflicted "bloody damage".
He said he believed these bombs could have been passed to protesters to set-off over the upcoming Lunar New Year holiday.
Ho linked the find to Hong Kong's recent social unrest, saying officers also seized helmets and leaflets with protest slogans on them.
He then alleged that the suspects may have been involved in riots in 2019 and 2020.
"From our investigation and intelligence, we think that they may have some connection in order to get hold of these explosives. And these suspects that we have in mind, they [are] somehow related or were involved in the rioting last year and the year before."
The senior superintendent said more arrests could follow and he condemns anyone who attempts to launch "bloody and violent attacks".