Medical professors, students and anti-smoking advocates rallied yesterday in support of the increase in tobacco duty, as another group of 500 people took to the streets in protest, saying the law 'discriminated against the poor'. Some 280 medical, nursing and Chinese medicine students from the University of Hong Kong and members of the Council on Smoking and Health submitted a petition to the Legislative Council, saying the tax rise would improve public health. The group argues that the 50 per cent increase in tobacco duty announced by the financial secretary in his budget a month ago would be effective in deterring youngsters and people from low-income families from smoking. The group then marched to the Central Government Offices and handed in its petition. On the other side of town, the League of Social Democrats organised about 500 people to protest against the tax increase, saying the absence of a similar rise in liquor duty was 'class discrimination'. 'Many smokers are from the working class or have lower incomes,' said league spokesperson Gavin Kwai Sze-kit. While not condoning smoking, the league said people were able to make an informed decision and the government was interfering with freedom of choice. Mr Kwai said alcohol consumption could lead to social problems such as family abuse. The league also wanted the government to extend the temporary smoking ban exemption for bars, saying the implementation of the ban on July 1 would cause many entertainment venues to go out of business. But medical experts replied that linking the tobacco tax to liquor was 'illogical'. Lee Sum-ping, HKU chair professor of medicine, said: 'When you drink wine, you won't affect others around you. But when a person smokes, [second-hand smoke] harms everyone around the smoker.'