A former head of China's National Bureau of Statistics has defended the country's official economic data against Western doubts on its credibility.

China says its economy expanded 6.9 percent year on year in 2015 despite leading indicators of economic activity, including rail freight volume and electricity use, falling significantly or barely advancing. Western journalists have questioned whether such a high GDP growth is possible given the other indicators.

"There are many barometers to measure GDP," said Ma Jiantang, now vice president of the Chinese Academy of Governance, at a news conference on Wednesday. "Indicators such as rail freight volume and electricity use no longer paint the whole picture."

Ma said the slowdown of these two indicators reflected industrial restructuring. Rail freight has dropped as coal production has been cut, while low electricity use also tallies with transition into a service-oriented economy, which is less reliant on power use.

Ma also said the 6.5-to-7-percent growth target set for 2016 was "reasonable" and took into consideration both domestic and global economic conditions. China's sound economic fundamentals, high savings rate, sufficient labor force and potential for innovation make the target achievable, according to the senior official.