Chinese President Xi Jinping says the global economy is being threatened by rising protectionism that hinders world trade.
Speaking on the opening day of the summit of leaders from the Group of 20 (G20) countries, he also said the global economy was "at a crucial juncture." He cited sluggish demand, financial market volatility, and feeble trade and investment.
At the two-day summit, the G20 leaders are expected to mount a defense of free trade and globalization and warn against isolationism.
Leaders attending include U.S. President Barack Obama, Russia's Vladimir Putin, Japan's Shinzo Abe, Britain's Theresa May, Germany's Angela Merkel, France's Francois Hollande, and India's Narendra Modi.
Security is extremely tight in Hangzhou, with parts of the city of 9 million people turned into a virtual ghost town as China seeks to ensure that the summit is incident-free.
Based on reporting by Reuters and AP