Hong Kong and Shenzhen need to work together to halt environmental destruction and pollution of the border area, the manager of the Mai Po Nature Reserve said yesterday. Dr Lew Young, manager of the World Wildlife Fund park in the northwest New Territories, said the area needed an overall plan. 'There is an unco-ordinated approach to development from both the Hong Kong and Shenzhen sides. 'Wet lands are being filled in and built on without much thought for what happens,' he said yesterday at the launch of the Discover Mai Po programme which encourages the public to visit the park. Dr Young criticised random construction on land in the border area and said a co-ordinated overseeing of development should be undertaken by the Hong Kong-Guangdong Joint Environmental Protection Liaison Group. 'We are not saying stop development but look at planning on a 'macro' scale because this area is so important.' The 1,500-hectare Mai Po site was declared a wetland of international significance last December.