(Reuters) - China’s President Xi Jinping has called for further development of the Yangtze River economic belt as part of the country’s “dual circulation” strategy, the official Xinhua news agency said on Sunday. Xi first raised the concept of dual circulation in May this year, amid a rift with the United States, and later explained China would rely mainly on “internal circulation” - the domestic cycle of production, distribution, and consumption - for its development, supported by “external circulation.” Speaking in Nanjing, capital of Jiangsu province, on Saturday, Xi said provinces and cities along Asia’s longest river - which flows from west to east China - should promote “coordinated development” and “guide the orderly transfer of capital, technology and labour-intensive industries in (Yangtze river) downstream regions to upstream and midstream regions.” They should also “actively open their markets to the world,” he said, according to Xinhua. The sprawling Yangtze economic belt spans 11 Chinese provincial-level regions and covers around 2.1 million sq km, accounting for 21% of China’s total land area and more than 40% of its population, according to state media.