Labour minister Chris Sun on Sunday rejected fresh calls to suspend the importation of workers, saying there was an acute labour shortage in many sectors.

This came after trade unionist lawmaker Bill Tang said imported labour for the catering sector should be suspended as many locals were concerned about their jobs.

Speaking on a TVB programme, Sun said the Enhanced Supplementary Labour Scheme already ensured that locals got priority, as employers can only import workers if they are unable to hire a local after a four-week recruitment exercise.

The minister told reporters the government had received more than a hundred complaints of employers sacking locals after hiring imported labour but that, so far, initial evidence suggested there had been just two such cases.

"Because we're talking about initial evidence, we cannot implement executive sanctions right away. We need to give the employers time to explain their case to us," Sun said.

"But given the evidence, we have put them on our watch list, which means their ongoing import applications have been suspended."

Sun said if the violations are substantiated, the authorities will impose sanctions "without hesitation".

That means all import applications for the employer concerned will be withdrawn and the employer won't be able to apply to import workers for two years.

Meanwhile, the minister said in another related case, an initial probe had found that an employer had refused to hire a local during the four-week recruitment period.

Sun said the authorities are now waiting for the employer's reply.