Immigration officers rounded up more than 80 people in a city-wide drive against illegal workers - and announced they would be stationing officers at black spots to stop illegal employment. The staff will be posted at Temple Street and Tung Choi Street in Kowloon, where more than 30 illegal workers have been caught in the past six months. 'Hopefully the move will deter employers from hiring illegal workers,' said senior immigration officer Pak Yuen-oug. Officers raided 74 locations on Monday and yesterday in an operation that continued last night. They arrested 87 people: 20 Hong Kong employers, 56 mainland visitors, nine foreign domestic helpers from the Philippines and Indonesia and two tourists from Nepal. Most of those arrested worked in shops and eateries; some were caught by undercover officers pretending to be customers. Other locations raided by the officers included flats under renovation, an unlicensed fast-food factory and an electronic goods packaging plant. Although the number of illegal workers arrested so far this year is similar to last year, the Immigration Department warned employers that it is getting increasingly common for job seekers to use fake identity cards. In the latest operation, officers seized 11 photocopies of fake identity cards. The actual cards had already been destroyed in the hope that would make the job of the officers more difficult. The department said offenders would still be liable for prosecution if the department could prove they used fake cards.