Beijing has warned Manila against any moves that may complicate or escalate tensions between the two nations, in response to the Philippines' seeking United Nations arbitration over its territorial claims.

China-Philippine ties were frayed last April after a Philippine warship first prompted a serious impasse in the waters off China's Huangyan Island in the South China Sea.

Observers said Manila's high-profile lawsuit was just "political posturing" and it has shown little willingness for one-on-one negotiations on relevant disputes.