BEIJING, Dec. 27 -- China will launch upgraded satellites and expand its regional BeiDou Navigation Satellite System (BDS) to global coverage by 2020, a spokesman for the system said on Friday.

"BDS' general performance is expected to be improved by one to two times from the current level and its positioning accuracy could be upgraded to meter or even sub-meter level" by 2020, BDS spokesman Ran Chengqi said at a press conference.

BDS began providing positioning, navigation, timing and short message services to civilian users in China and surrounding areas in the Asia-Pacific region in December 2012.

Over the past year, positioning has been accurate to within ten meters, according to Ran, director of the satellite navigation office.

"Performance is better in some regions," he said. Accuracy can reach seven meters in Chinese cities like Beijing, Zhengzhou, Xi'an and Urumqi and five meters in low-latitude regions such as the Association of Southeast Asia Nations (ASEAN).

The office issued an interface control document (ICD) for open service signal B2I in both Chinese and English on Thursday.

"B2I, which updates B1I released last year, means BDS has entered the era of multifrequency application," Ran said. "It means the system can provide more accurate navigation."

Companies from both home and abroad could develop high-precision dual-frequency BDS receivers on the basis of this, according to the spokesman.

China launched the first BDS satellite in 2000. Prior to the official launch of the system a year ago, a preliminary version of the system has been used in traffic control, weather forecasting and disaster relief work since 2003.