China's crude oil output saw steady expansion, rising 4 percent year on year in the first six months, official data showed.

The output totaled 102.88 million tonnes from January to June, according to the National Bureau of Statistics.

In the same period, China imported 252.52 million tonnes of crude oil, down 3.1 percent year on year.

In June alone, China's crude oil output went up 3.6 percent to 17.19 million tonnes, while crude oil imports fell 10.7 percent to 35.82 million tonnes, the data showed.