The overseas oil and gas output of China National Petroleum Corp - the country's largest energy producer - was more than 100 million metric tons for the first time ever in 2013, as the company is boosting its international presence.

CNPC said on Friday that its total overseas oil and gas operational output for last year was 123 million tons, up 18.1 percent year-on-year, with its equity share of that at 59.2 million tons.

Zhou Jiping, CNPC's chairman, said at the company's annual working conference on Thursday that 2013 was a special year with many challenges.