-- China National Petroleum Corp., the nation's biggest oil producer, said its first-half natural gas output rose 18 percent, or 4.6 billion cubic meters, as energy demand increased in the world's fastest-growing major economy.

The parent of Hong Kong-listed PetroChina Co. met 50 percent of its annual target in crude oil production in the first six months, China National said in a statement on its Web site today. Its first-half oil output increased by 466,700 metric tons, the company said.

Chinese oil companies are expanding production to help ease an energy shortage in an economy that expanded 10.6 percent in January to March, the ninth quarter of double-digit growth. Chinese oil demand is expected to increase 5.6 percent this year as consumers buy cars and travel more, according to the International Energy Agency's forecast yesterday.

China National completed 79 percent of its refinery maintenance planned for this year in the first half, and operated its plants at ``high rates,'' it said.

The company's overseas proven oil reserves added in the first half accounted for 51 percent of its annual target, it said. It met 54 percent of its annual target in natural gas production from overseas fields in the first six months, according to China National.

China National will increase exploration efforts and ensure ``safe and stable'' fuel supplies in the second half, it said.