Hong Kong beaches and fisheries could be under threat because an oil spill in waters south of the city is proving difficult to control, mainland authorities acknowledged yesterday. A collision between two ships early last week caused the spill. By Sunday, the size of the fuel oil leak from a German-registered ship was reported to be 1,200 tonnes. Officials have not updated the leak's size since then. The collision happened less than 5km from the southern boundary of Hong Kong waters. The leaking ship had since drifted a further 8km to the southwest. Xu Guoyi , deputy director of the ministry's Maritime Safety Administration, was quoted by state television as saying that bad weather had held up efforts to fully contain the spill - the largest in China's history. 'If it gets to Hong Kong waters, the contamination will cause huge economic loss to its tourism industry and seawater aquaculture,' he said.