WASHINGTON, Oct 6 (Reuters) - The United States and China reached an agreement in principle for U.S. President Joe Biden and Chinese leader Xi Jinping to hold a virtual meeting before the end of the year, a senior U.S. administration official said on Wednesday. The official made the comment to reporters following a meeting between U.S. national security adviser Jake Sullivan and China"s top diplomat Yang Jiechi in Switzerland, talks intended to improve communication despite a deepening rivalry between the two countries. read more Reporting by Michael Martina, Steve Holland, and Daphne Psaledakis in Washington