The multimillion-dollar Peak residence of one of the mainland's richest men was raided by burglars early yesterday who tied up two domestic helpers and then emptied his safe. Hui Wing-mau, 52, chairman of listed company Shimao China Holdings, was named by Forbes magazine as the fifth-richest man on the mainland with an estimated fortune of US$700 million (HK$5.45 billion) in 2001. Neither he nor his family were in the four-storey house in Mount Austin Road at the time of the robbery. Yesterday evening, his secretary, Stella Chui, confirmed that Mr Hui's home had been broken into. She said Mr Hui, who was on the mainland at the time, had been alerted but she declined to reveal when he would return to Hong Kong. A police source said that three Cantonese-speaking intruders - wearing white surgical masks, gloves and hats - took almost an hour to break into the safe before fleeing with jewellery. Officers said they had not established how much the jewellery was worth or whether other valuables had been stolen. The robbers entered the house at about 3am. Its alarm system was not turned on, the source said. The burglars climbed up drainpipes and entered through a third-floor bathroom after they apparently failed to prise open a second-floor window. Two went straight to the ground-floor maids' room where they woke up two Indonesian helpers, aged 26 and 36, and tied them up. No weapons were used during the burglary. 'The helpers had their arms and legs bound with ties and their heads were covered with clothes,' the source said. The helpers were then taken to the second-floor master bedroom where a third robber was waiting. Another source said the raiders then moved a safe from the dressing room to the bathroom where they tried to break it open. 'They fled with the valuables following the same route they had used to enter the house,' the source said. 'It appears the robbers knew the layout of the house and what they were looking for.' Yesterday's robbery is the first reported on the Peak in 15 months, according to an officer from the Peak police station.