An extra 500 housing officers and engineers will be on duty to guard against any Y2K-induced disasters, the Housing Department said. An emergency centre manned by 50 staff at the headquarters will be on full alert from 10pm on December 31 until 7am on January 1. Cheung Woon-hang, chief systems manager of the department's computer division, said: 'We shall spare some five to six people as messengers in case all telephones, mobile phones, computers, or whatever are down. We shall send our messages by hand.' Leaflets will be distributed next month telling tenants who to report to in case of trouble.