The administration of U.S. President Joe Biden has proposed to Japan, Australia and India that the first in-person "Quad" meeting of the countries' leaders be held in Washington in late September, according to diplomatic sources.

The face-to-face meeting will follow the first-ever Quad summit that was conducted virtually in March. The gathering would underscore the unity among the four Indo-Pacific democracies amid China's growing assertiveness.

Biden is seeking to build "a position of strength" to directly engage with Chinese leader Xi Jinping, possibly on the sidelines of the Group of 20 summit in Rome in late October.