A district councillor and his aide were robbed at knifepoint of a watch, $7,200 and three phones in his Tuen Mun office yesterday. Ng Koon-hung, 48, an independent, and his assistant, Ng Wai-lan, 45, were having a meeting in the ground-floor office of King Kwai House, Shan King Estate, at 10.30am when a man wearing a surgical mask and cap burst in. He threatened them with a knife and demanded valuables and money. 'The robber hit the female victim with the handle of the knife, ordering her to take off her watch quickly,' said Detective Chief Inspector Cheung Yiu-sang, of Tuen Mun police. The robber was given two watches, two wallets and three mobile phones. He fled with the items in a green cloth bag. Inside the wallets were cash, bank cards and identity cards and Ms Ng's home return permit. The councillor called police and more than 50 officers, including members of the Police Tactical Unit, mounted a search. But they were unable to find the culprit. Mr Ng was unhurt, but his assistant was treated for head injuries. The robber, a Cantonese speaker, was wearing a checked shirt and was described as being about 40 years old and of thin build. The councillor expressed his anger, saying he had been attacked while working for the public. Last night detectives were checking tapes from surveillance cameras at the estate in an attempt to identity the robber.