Police said on Tuesday 99 people have been arrested on suspicion of manufacturing, trafficking and possession of dangerous drugs in citywide operations over the past month.

Officers seized 220 kilogrammes of drugs worth over HK$110 million.

They included cocaine, cannabis buds, methamphetamine, ketamine and space oil.

Nineteen of the suspects were under 21, with the youngest being just 13 years old.

In one undercover operation, officers dismantled a drug syndicate operating on social media platforms that had storage facilities in Yau Tong and distribution points in Kai Tak.

Regarding the involvement of minors in drug trafficking, police said heavier penalties would be sought under the Dangerous Drugs Ordinance.

The force said it's working with schools and social workers to raise awareness about emerging drugs like space oil.

"Police will continue taking a zero-tolerance approach in combating drug-trafficking activities, including those conducted through the internet and social media," said Ho Ho-ting, a senior inspector from the Narcotics Bureau.

"Drug dealers who try to hide behind computer screens while getting others – including teenagers – to sell drugs for them are fooling themselves if they think they won't get caught and face consequences."