Foreign Minister Wang Yi said Beijing has made its strongest diplomatic effort to try to avert the current cross-strait crisis, but made it clear it will never allow its core interests to be undermined.

Speaking in Cambodia where he attended a meeting of ASEAN foreign ministers, Wang again condemned US House Speaker Nancy Pelosi's trip to Taipei, calling it a provocation and a violation of international law and bilateral agreements.

He described the US action as "manic, irresponsible and highly irrational" and said it must be firmly opposed in order to protect sovereignty, territorial integrity as well as regional security.

Wang called the United States "the biggest troublemaker" when it comes to regional security. (Additional reporting by Reuters)