By Danny Kemp and Isabel Kua, AFP

China's President Xi Jinping (R) warned US President Donald Trump that the issue of Taiwan could push their two countries into "conflict" if mishandled, a stark opening salvo as a superpower summit set to tackle numerous thorny issues began in Beijing on May 14.

US President Donald Trump on Friday warned Taiwan against declaring formal independence after concluding his visit to China, whose leader Xi Jinping had pressed him not to support the self-ruling island.

Trump ended the state visit claiming to have made "fantastic" trade deals, although the details were vague, and he did not appear to secure any breakthrough with China over his stalemated war on Iran.

Trump invited Xi for a reciprocal visit to Washington in September, signalling both sides will likely seek stability in the often turbulent relationship between the world's two largest economies.