China's positioning of its biggest mobile oil rig in disputed waters in the South China Sea seriously threatens peace, stability, and maritime safety, Vietnam's prime minister said on Wednesday, urging the international community to condemn Beijing's action. Nguyen Tan Dung held two-way talks with Philippine President Benigno Aquino during an official two-day visit to Manila to discuss defence and security and economic and cultural ties. "China's illegal placement of the oil rig seriously threatens peace, stability, maritime safety and freedom of navigation in the East Sea," the Vietnamese prime minister said in a statement after the meeting at the presidential palace in Manila.