BEIJING - CNOOC Limited, China's largest offshore oil and gas producer, announced Tuesday that its unaudited sales revenues rose 3.7 percent year-on-year to hit 48.84 billion yuan ($7.8 billion) in the first quarter.

The revenue increase came alongside rising sale prices of oil and natural gas. During the first quarter, the company's average oil price rose 19.4 percent to $120.79 per barrel while that of natural gas increased 19.8 percent to $5.88 per 1,000 cubic feet (28.3 cubic meters), the company said in its quarterly report.

The company said that production during the period dropped 6.3 percent to 79.8 million barrels of oil equivalent following a major oil leak at the Penglai 19-3 oilfield in north China's Bohai Bay last year. The oilfield is jointly-owned by CNOOC and the Chinese subsidiary of US oil giant ConocoPhillips.

Li Fanrong, CNOOC chief executive officer, said that CNOOC also made major oil and gas discoveries in the first quarter, which are expected to propel the company's production during 2011-2015. The company aims to boost production during the period by 6-10 percent.