A hi-tech device will be used to spy on some government workers in a blitz on lazy staff. A computerised device will be installed in the 25 Urban Services Department street-cleaning or drainage clearing vehicles to record every movement and detail of its operations. Similar to the black box installed in an aeroplane, the device can record the time of the movements of the vehicle, speed, and the pieces of equipment used. A pilot scheme is expected to be launched in the middle of this year. The move comes amid a disciplinary probe into claims some overnight workers were playing cards during office hours. The controversy broke after provisional urban councillors conducted a surprise blitz last month at the department's Mongkok depot. The councillors said they saw some overnight-shift drain cleaners playing cards or sleeping after clearing a drain outside their office. The department's deputy director, Michael Arnold, who is leading the in-house disciplinary probe, said officers at the Mongkok depot had been interviewed. A separate inquiry has been launched by councillors, and Mr Arnold is expected to be summoned to give statements next month. He said the department was studying new measures to boost efficiency and cut costs. Among the high-technology options are robot street sweepers and the spy device. He said it was considering allowing private firms to take over more of the municipal services. Overnight-shift services would be contracted out first. But Mr Arnold said he would opt for a gradual approach. 'Contracting out is complicated, although it may look as simple as drafting an agreement or contract. 'We have 4,000 staff members providing the services of cleansing. They are civil servants and they are entitled to a career. We cannot simply fire them all and contract out our jobs'.