Veteran green advocate Peter Wong Hong-yuen will step down as head of the top government advisory body on the environment when his term expires at the end of the year. His decision not to seek another term has raised fears among green groups that the Advisory Council on the Environment's aggressive role will be undermined. 'I should make way for someone else,' said Mr Wong, who has been chairman for almost six years. 'It'll force the Government to start thinking who else is suitable. We need some new changes and new ideas. I'll be happy to step down.' The news comes as council members believe it is time to review how to strengthen its operation after the Lok Ma Chau spur line controversy. The Conservancy Association's Dr Ng Cho-nam, another tough-minded environmentalist, will also see his term expire in December. He was an outspoken critic of the spur line project and of KCRC chairman Yeung Kai-yin. Mr Wong's decision is being seen by some members as a blow to green groups' influence. 'Mr Wong has brought major changes to the council by making it assume a more pro-active role,' said Dr Ng. Another council member, who preferred not to be named, warned that control of the council might be tightened by the Government. 'He [Mr Wong] is regarded as a liberal on environment issues. But in the eyes of officials, his style is seen as inefficient and wasting time.' Professor Ng Ching-fai, president of Baptist University, and Raymond Ho Chung-tai, the legislator representing engineers, are possible candidates for the post.