Net profit at China National Offshore Oil Corp (CNOOC) rose 7.9 percent in the first half of 2013, the company said Tuesday.

Net profit hit 34.4 billion yuan ($5.6 billion) in the first half and sales revenue grew 15.8 percent to 110.8 billion yuan, the country's largest offshore oil producer said in a statement.

The company's crude oil and natural gas output was up 23.1 percent year on year to 198.1 million barrels of oil equivalent, including 24.8 million barrels of oil equivalent from Nexen, the statement said.

On Feb 26, CNOOC closed a $15.1 deal with Nexen Inc in Canada, marking the biggest overseas acquisition made by a Chinese company.