Cambodia hopes to look for oil and gas near its Tonle Sap great lake, but the head of the petroleum authority said yesterday he was confident exploration and exploitation would not damage the lake's environment. An airborne magnetic and gravity survey, funded by Japanese aid, began in 1996 but ended in 1997 when the contractor's plane crashed into a mountain south of the lake, the director general of the National Petroleum Authority said. The survey, though incomplete, showed there was potential for oil and gas, and Cambodia was now hoping to do some seismic exploration of the area, he said.