THE Planning Department yesterday promised a quick response to complaints about unauthorised use of land in the New Territories - but one critic said it would be meaningless unless action was taken to end illegal development. The New Territories landscape has been scarred by the illegal conversion of fishponds and rice paddies into container storage lots and junkyards. In some cases, landowners have blatantly flouted the law but were still not prosecuted, although a task force set up by the Governor in October is expected to address the land use issue. The Director of Planning, Dr Peter Pun Kwok-shing, said his department would respond to reports from the public on unauthorised developments within four weeks, but he could not promise quick enforcement. But Billy Hau Chi-hang, conservation officer for the World Wide Fund for Nature (WWF), said that was not good enough. The WWF has filed complaints about illegal land use and has seen the Planning Department take up to a year to contact owners. ''If they take four weeks to tell you something is illegal but don't take any action to stop the activity, it's meaningless,'' he said. Dr Pun said enforcement was complicated because the relevant land may have several owners and the boundaries may be uncertain. He also said they needed at least 50 more staff to meet the objectives of the task force in controlling New Territories development.