Philippine President Rodrigo Duterte announced his "separation" from the United States on Thursday, declaring he had realigned with China as the two agreed to resolve their South China Sea dispute through talks.

Duterte made his comments in Beijing, where he is visiting with at least 200 business people to pave the way for what he calls a new commercial alliance as relations with longtime ally Washington deteriorate.

"In this venue, your honours, in this venue, I announce my separation from the United States," Duterte told Chinese and Philippine business people, to applause, at a forum in the Great Hall of the People attended by Chinese Vice Premier Zhang Gaoli.

"Both in military, not maybe social, but economics also. America has lost."