Immigration officers arrested 18 illegal workers and eight employers in anti-illegal work operations on July 27 and 28.
They raided 19 locations, including restaurants, a massage centre, a warehouse, an office and factory units, and arrested 11 illegal workers and eight employers.
Three men and one woman held recognisance forms which prohibit employment, while four men and three women were suspected of using and being in possession of forged Hong Kong identity cards.
Officers also arrested seven Mainlanders for parallel goods trading in Sheung Shui and Lok Ma Chau.
The department reminded employers not to hire illegal workers and warned visitors not to take up employment in Hong Kong without permission from the Director of Immigration.