Chief Executive John Lee says the government will protect all workers employed in Hong Kong and punish any violators of labour laws stringently, following complaints that some imported workers have been exploited.

Earlier this month, unions reported that some mainland workers have been made to work extra shifts for no pay, while others have been denied some of their salaries or had their ATM cards confiscated.

Lee noted that an inter-departmental investigative team has been formed on the matter, involving the police and other law enforcement agencies, as well as labour and development officials.

"In fact, we can see that many of the cases involve, for example, agents, agencies or intermediaries. We will handle them seriously according to the law if they violate the system or even the law," the CE said before the weekly Executive Council meeting on Tuesday.

"Under suitable circumstances, we will inform the mainland authorities so that we can ensure the operations comply with our requirements."

Lee said while workers from elsewhere are needed, the employment of locals remains a priority, noting that the latest batch of construction industry applications was rejected.

"We have to balance between the protection of local [labour] and ensuring that we have enough workers to support our economic development as well as the running of businesses," he said.

"We will approve [import applications] very stringently and carefully. For example, in the last exercise when the construction employers tried to apply, no approval was given because it was assessed that some of the construction sites actually won't start yet."

Lee also reiterated that the city's special labour import schemes have built-in safeguards for local workers.

These include imported workers getting paid no less than the industry's median wage, and that imported labour can only be sought when attempts to recruit local workers have failed.