A proposed scheme to register qualified site workers could be abused by employers to exploit workers and force down wages, a legislator has warned. About 80,000 local construction workers will have to pass tests in three years to be qualified as skilled, semi-skilled, or general workers to work on sites. The proposed system is aimed at upgrading the quality of site workers and providing data for staff planning or training, according to officials. It was tabled at yesterday's special meeting of the Legislative Council planning, lands and works panel. Under the proposal, site workers with a minimum six years' experience can apply to register as skilled workers, while those with two years' experience can apply to register as semi-skilled staff. They will have three years to pass respective trade tests. Those failing the tests could still become general workers, but would have to be supervised by a qualified skilled worker when working on sites. Exemption will be offered to workers with 10 years' experience, who can register as skilled workers after an interview. Registration would be renewed every three years. The Deputy Secretary for Environment, Transport and Works, Chan Wing-sang, said it was estimated that about 50,000 out of the 80,000 site workers had not yet taken the government-recognised trade tests. Mr Chan said a three-year grace period should be long enough for all workers to upgrade themselves and become qualified. But panellist Albert Chan Wai-yip of the Democratic Party warned that contractors could abuse the registration scheme to cut workers' wages or sack them. 'For those who cannot get registered as skilled workers, they might have their wages slashed or might be fired. The government should assess the impact on the workers,' he said. Fellow panellist, unionist legislator Leung Yiu-chung of the Neighbourhood and Workers' Service Centre said: 'Site workers are hired by sub-contractors who are given the job by another sub-contractor. How can workers trace their bosses to get the necessary proof that they have been in the trade for 10 years?'