Immigration Department has raided 14 places in a city-wide anti-illegal worker operation, resulting in the arrest of 11 suspected illegal workers and four local employers.

The operation began at 9am and ended at 4.30pm today. Immigration investigators raided 14 targeted locations including commercial premises and residential flats under renovation.

As a result, 11 Mainland visitors - 10 men and one woman aged 18 to 49 - were arrested for suspected breach of conditions of stay. Most of them came from Guangdong and Fujian.

Officers also arrested four male Hong Kong residents, aged 32 to 52, suspected of employing illegal workers.

Visitors are not allowed to take up employment, whether paid or unpaid, without the prior permission of the Director of Immigration. Offenders are liable to prosecution and, upon conviction, to a maximum of $50,000 fine and two years' jail. Aiders and abettors are also liable to prosecution and penalty.

It is also an offence to employ people who are not lawfully employable. The maximum penalty is a $350,000 fine and three years' jail.