Service trade figures were not included in the calculation of China's trade surplus, causing it to become overvalued and creating a distorted picture of the country's foreign trade, a former commerce official said Wednesday.

Incomplete statistics showed that China's service trade sector experienced a deficit of about 60 billion U.S. dollars last year, compared with a surplus of 115.1 billion U.S. dollars in traded goods, said Ma Xiuhong, former vice minister of commerce.

Ma, who is also a member of the National Committee of the Chinese People's Political Consultative Conference (CPPCC), China's top political advisory body, urged the government to start including service trade volume in calculations of the country's trade surplus.

The actual surplus would fall below 60 billion U.S. dollars after taking the deficit into account, Ma said at a panel discussion of the CPPCC's ongoing annual session.

China's trade surplus has increased trade frictions and put pressure on its economic policies, Ma said.

"The calculation is not only a matter of statistics, but something that affects the trade situation and changes global attitudes," Ma said.