PetroChina, China's largest oil producer, has made the nation's biggest oil discovery in a decade, finding an estimated reserves of 430 million tons in northwest China.

The big discovery boosts its reserves by at least 30 percent at a time when oil prices are at a record high and the country's fuel demands are soaring.

PetroChina Changqing Oilfield, a unit of the Beijing-based company, found 108.2 million tons of proven reserves and another 327 million tons of estimated reserves in the Xifeng oilfield in the northwestern province of Gansu.

The new field would be sufficient to meet China's current level of consumption for one and a half years.

An energy analyst says the discovery dispels rumors that PetroChina's oilfield reserves are being depleted.

China's oil imports may rise 9.8 percent this year to 100 million tons and the country may burn as much as 270 million tons of fuel.