Contractors have called for restrictions on hiring overseas workers to be relaxed after a study showed local workers were becoming less efficient, partly because of a lack of skills. Measures to clean up Hong Kong were also partly to blame for falling productivity in the construction industry, according to a study released yesterday. The study, commissioned by the Hong Kong Construction Association and the Hong Kong Economic Times, showed the sector's productivity had dropped by 10 per cent between 1994 and 1998. Measured by output-to-input ratio, the fall in productivity means the same amount of money or materials pumped into the building sector is producing fewer buildings, roads or bridges. Association president Jimmy Tse Lai-leung said the decline was worrying. 'Our productivity has dropped to the level of 10 years ago. The Government must do something in time,' Mr Tse said. He attributed the problem partly to a shortage of skilled workers and urged the Government to be more flexible when allowing contractors to import workers. He said tight environmental protection rules on sites had delayed projects, reducing productivity. But he was quick to emphasise that a better environment would do more good than harm to society in the long-term. Researcher Professor Anthony Walker, of the University of Hong Kong's department of real estate and construction, said the industry should pay more attention to research and development. The construction industry contributes about six per cent of Hong Kong's gross domestic product, according to the report. A committee chaired by Executive Councillor Henry Tang Ying-yen is now conducting a review of the local construction sector. The chief executive of the Construction Site Workers' General Union, Sung Chee-tak, accused the association of making an excuse to import cheap labour. 'The Construction Industry Training Authority is producing lots of skilled workers every year. There is no question of Hong Kong lacking skilled workers.'