GUANGDONG officials rushed yesterday to clarify a ban on new thermal power plants in the Pearl River Delta amid concerns from investors. The province's Environmental Protection Bureau, which announced the ban to reduce acid rain in the delta, said it would mainly restrict the construction of small power plants of 100 megawatts or less. Large-scale power plants and those projects that had already been approved would be allowed to proceed, said Li Zhiyan, a spokesman in the bureau. 'In recent years, thermal power plants in the delta region have grown raising emissions levels of sulphur dioxide and exacerbating the problem of acid rain,' Mr Li said. Some investors have tried to evade the central government's efforts to cut spending on capital construction by building several small power plants, which can be approved at the provincial level. The small plants are less efficient than larger ones. Mr Li said that large-scale coal, oil and gas power plants would also face a more rigorous application process. More thermal power plants would have to be built outside the delta region, and the government would place a higher priority on hydroelectric power than it had in the past. Mr Li said power plants would be required to burn coal more cleanly. Wu Xirong, head of the Guangdong Electric Power Bureau, said the development of power projects in the province would proceed according to the original plan despite the ban. An official of the Energy Department of the Guangdong Planning Commission said the ban was limited to nine cities in the region, not the entire Pearl River delta. Su Deju, director and general manager of the Guangdong Electric Power Development Co, said the ban would not affect his company's plans for future power projects. Guangdong Electric is planning on listing B shares in Shenzhen later this month.