A summit of at least 20 nations is planned on the sidelines of the U.N. General Assembly this month to seek ways "to talk some sense" into China over its confrontation with the Philippines in the South China Sea, Manila's Washington envoy said on Tuesday.

"The more countries band together and give a message to China that what they're doing is definitely not on the right side of history, then we have a better than even chance that they will not make that wrong move that we're all fearing," the envoy, Jose Manuel Romualdez said.

Romualdez did not elaborate on plans for the summit, which he said would take place on the sidelines of the annual General Assembly in New York in the week of Sept. 22.