WASHINGTON/BEIJING - China has seen its national image improve in recent years thanks to strong economic growth, but the country needs more persistent and practical efforts to maintain this progress in the years to come, observers said.

The 2011 Anholt-GfK Roper Nation Brands Index (NBI), released on Wednesday, indicated a slight improvement in China's image, ranking 22nd, compared to 26th in 2008.

The survey has measured the global image of 50 countries annually since 2008, and is conducted among citizens in 20 major countries, including 11 developing countries.