Verbal attacks against legislator Emily Lau Wai-hing of The Frontier have escalated into violence. The door to her Sha Tin district office was smeared with faeces last night. The incident, at the ground-floor premises in Hok Sum House, Lung Hung Estate, was discovered when a woman assistant returned from dinner at 8.30pm. A report of the incident was made at Tin Sum police station. It is not the first time Ms Lau's Sha Tin office has been vandalised. In July, a report was also made to the police after leftover food was smeared on windows. A piece of paper wrapped round a lump of concrete was found hanging on the door bearing the words ' Emily Lau is a traitor'. Last night, Ms Lau said: 'I have all along been worried that such a thing would happen. It started with verbal attacks and now it has escalated into violent action. Is Hong Kong still a place with rule of law?'' The lawmaker triggered controversy after she attended a seminar held in Taipei by the Taiwan Advocates, a pro-independence think-tank led by former president Lee Teng-hui. On the question of re-unification, Ms Lau said she would respect the Taiwanese people's choice. Pro-Beijing figures yesterday continued to criticise Ms Lau. Maria Tam Wai-chu, a member of the Basic Law committee, said lawmakers should abide by their oath of supporting national unity and the 'one country, two systems' policy. Ms Lau has been accused of breaching the lawmakers' oath to uphold the Basic Law. The Legislative Council has received letters of complaint from people demanding the lawmaker's resignation. Some legislators have vowed to debate the controversy over her Taiwan visit. Executive councillor Andrew Liao Cheung-sing said yesterday officials and lawmakers should support reunification.