The Immigration Department arrested 19 suspected illegal workers and two local employers and raided an unlicensed cooked food centre in Mong Kok in a city-wide operation yesterday.

The operation, codenamed "Twilight" started at 7.45am and ended at 6.15 pm. Officers raided 21 targeted locations in Tsuen Wan, Sha Tin, Kowloon East and West, including restaurants, food stalls and flats under renovation.

In Mong Kok, officers stopped two men and one woman on the street who were providing delivery service for a cooked food centre. Officers also raided a residential flat on Dundas Street and found eight others - seven Mainland visitors and a Thai overstayer.

As a result, 19 people - 11 men and 8 women, aged 21 to 46 - were arrested for suspected breach of conditions of stay. Two male Hong Kong employers, suspected of employing illegal workers, were also arrested. All are being detained for further enquiries.

The department reiterated visitors are not allowed to take up employment, whether paid or unpaid, without the prior permission from the Director of Immigration.

Offenders are liable to prosecution and, upon conviction, to a maximum fine of $50,000 and two years in prison.

It is also an offence to employ people who are not allowed to work here. The maximum penalty is a $350,000 fine and three years in jail.