They are believed to have been involved in 21 cases including theft, stealing inside cars, deception and fraud.

Apart from targeting those drunk after a night out, they also stole from drivers who forgot to lock their cars, or ones who fell asleep inside their vehicles at night.

Yau Tsim Mong police arrested the four men, including a Chinese mastermind and three Indians who have resided in Hong Kong for more than 10 years, in an operation on Tuesday.

Police superintendent Chan Sai-cheung said more arrests could be made, adding that the group had two tactics - stealing phones, wallets and other valuables from people who were drunk or collapsed on the street, and taking advantage of drivers who forgot to lock their car doors or fell asleep.

The thieves subsequently used the stolen credit cards to purchase gift cards at convenience stores or conducted unauthorized transactions online, causing the victims to lose even more.

The three Indian suspects then passed the stolen identity and credit cards to the alleged mastermind.

Chan said during the arrest, the mastermind attempted to hide his identity by displaying a stolen identity card to the officers.

More stolen identity cards were found at his home in Sham Shui Po, which are believed to have been used to fabricate address proofs and employment certificates in order to apply for loans and credit cards from banks and financial companies.

"Citizens should lock the doors of their cars when leaving vehicles and not leave valuable belongings in them. Convenience store staff should confirm the identity of credit card owners during transactions," Chan said.

They also advised convenience store staff to report any suspicious customers to the police.