Green activists yesterday stepped up pressure on the government to reject the environmental impact assessment report on the planned third runway at Chek Lap Kok, questioning the way the government's advisers endorsed the report. But they said they had not yet decided whether to launch a legal challenge if the report was accepted by the director of environmental protection later this month. The call followed the endorsement by the Advisory Council on the Environment last month of the Airport Authority's study of the assessment. "I regret the council's decision," Dolphin Conservation Society chairman Dr Samuel Hung Ka-yiu said. "We just can't accept it. What the authority did was just camouflage to conceal [the fact that it] had nothing to offer at all," he told a special meeting of the Legislative Council's economic development and environmental affairs panel. The meeting also heard from supporters of the runway - mostly from the aviation and logistics industries - who said Hong Kong would pay a high economic price if the project was dumped. "We have learned a painful lesson of losing our port business to Shenzhen after we hesitated over whether to build more port terminals," said Pang Chor-fu, an executive director of the Hong Kong Chinese Importers' and Exporters' Association. Cathay Pacific and its subsidiaries and unions also backed the project, as did taxi groups. Green activists said they would not blindly oppose development but felt it was time to reconsider Hong Kong's practice of using infrastructure projects to drive economic growth. They also questioned whether the council had acted within the law in endorsing the report. WWF Hong Kong marine conservationist Samantha Lee Mei-wah urged the director not to approve the report, which she said was "substandard". Tang Kin-fai, assistant director of environmental protection, said the department and the council had both adhered to the law. "There was neither concealment nor conspiracy," he told lawmakers at the meeting. The third runway project will require reclamation of 650 hectares of sea that is a known habitat for the threatened Chinese white dolphin.