Environmental groups accused the Airport Authority of insincerity and a lack of preparation at a meeting on the planned third airport runway yesterday. They said the authority had not addressed demands raised a month ago. The nine groups that met authority representatives said they would continue to boycott its technical briefing group unless it made a greater effort to answer their concerns. The groups had set the authority "12 tasks" a month ago, but no deadline to meet them, said Angus Ho Hon-wai, of the group Greeners Action. "We sent them a letter a month ago requesting a meeting and stating our demands, but they seemed unprepared [yesterday]," he said. "We didn't give them a deadline, but we hope the authority can show some commitment in the coming weeks." The groups are seeking more details about noise and air pollution, carbon emissions, impact on fisheries and dolphins and mitigation measures for environmental damage. They have also requested data on aircraft movements, noise and expected air quality during construction. Ho said the authority only committed to calculate the extra carbon emissions from the third runway at yesterday's meeting. In response to the criticisms, the authority said it was sincere about engaging stakeholders, including green groups. The social impact assessment would be done around the completion of the environmental impact assessment, it said. The authority also briefed media yesterday on updates to designs for the third runway. The area needing reclaiming on the northern side of the third runway would be reduced, but the western end of the existing north runway would be extended slightly to provide an additional taxiway. The total area of reclamation would stay under 650 hectares, said Kevin Poole, the authority's deputy director of projects.