Chinese President Xi Jinping has officially opened a two-day summit of the world's major economies, saying the Group of 20 should adopt new measures to generate growth momentum and avoid protectionism. 
The 11th G-20 economic forum takes place in the eastern Chinese city of Hangzhou. 
In opening remarks, President Xi said the world economy is recovering but faces multiple challenges in finance, trade and investment. 
He said the summit will discuss innovation-driven growth and more efficient global economic and financial governance. 
The G20 leaders are expected to discuss how to deal with the downside risks brought about by the economic slowdown in emerging economies, Britain's decision to leave the European Union, and frequent terrorist attacks around the world. 
The focus will be on how clearly the participants can agree to work together to tackle these issues. 
The summit will close on Monday after the leaders adopt a declaration.