Police say they are cracking down on illegal practices by taxi drivers, to try to stop tourists getting ripped off during the mainland's upcoming National Day holidays.

At a press briefing on Wednesday, officers said they received around 2,700 complaints about taxi drivers in the first eight months of the year, about things such as overcharging and longer routes than necessary.

Since their operation began last Friday, three drivers have been arrested on suspicion of overcharging after officers posed as passengers, the force said.

Another seven people were arrested on suspicion of operating or promoting unlicensed cabs.

"The operation aims to enhance road safety, smooth traffic flow for all citizens and tourists, as well as for betterment of visitors' experience during their stay in Hong Kong," said superintendent Nip Hoi-kwan.

"The operation will continue until the end of the National Day Golden Week and police will take action against all illegal activities from time to time".