China's output edged down 1.6 percent year on year in May to 15.97 million tonnes, narrowed from a 2.3-percent decline in April, data from the National Bureau of Statistics (NBS) showed.

China produced 515,000 tonnes of crude oil per day in the month, compared to 517,000 tonnes for April. The daily crude oil output had stayed at around 515,000 tonnes for five months in a row, said the NBS.

In May, the country's crude oil imports gained 5 percent year on year to 39.05 million tonnes, the NBS data showed.

In the first five months this year, the country's crude oil output declined 2 percent to 78.23 million tonnes, while the first four months saw crude oil imports decrease 2.1 percent, according to the NBS.

From January to May, China's crude oil imports increased 8 percent year on year to 190 million tonnes, the NBS data showed.

International crude oil prices were on an upward trend in May. At the end of the month, crude oil prices stood at 76.45 U.S. dollars per barrel, compared to 75.92 a month ago.