HONG KONG - The territory arbitration initiated by the Philippines over islands in the South China Sea lacks legal backing and violates a joint declaration co-signed by China and all ASEAN member states, a Chinese diplomat said Friday.

Song Ruan, deputy commissioner for China's Foreign Ministry in Hong Kong, told a foreign press briefing, ahead of an anticipated ruling by an international court over territorial disputes with the Philippines, that the islands in dispute do not fall within the Philippines' territory and China will not accept the ruling.

"The arbitration unilaterally initiated by the Philippines is illegal," Song said. "The South China Sea islands and Huangyang Island (Scarborough Shoal) mentioned in the arbitration case simply do not fall into the Philippines' territory defined by the three treaties."

He said three international treaties, including the 1898 Treaty of Paris, "clearly set 118 degrees east longitude as the western limit of the Philippine territory."

"The Constitution of the Philippines before 1997 and its maps published before the 1970s were consistent with such definition. Besides, the South China Sea dispute is, in essence, a territorial issue, which is not subject to the UNCLOS," Song said, referring to the U.N. Convention on the Law of the Sea.

He added that China declared in 2006 under the UNCLOS to exclude compulsory arbitration, and the Philippines' unilateral initiation of arbitration is "imposing its own will on others" and therefore China will not accept or recognize the result of the arbitration "whatever it might be."

Song also said under the "Declaration on the Conduct of Parties in the South China Sea" China signed with 10 ASEAN member states, including the Philippines, in 2002, and a joint statement concerning the South China Sea which China reached with the Philippines alone, territorial disputes should be resolved through consultations and negotiations, and the Philippines' unilateral arbitration submission "violates the principle of (estoppels) in international law."

China has been aggressively pursuing its claims in the South China Sea in recent years, including within what the Philippines claims as its exclusive economic zone.

In 2013, after China wrested control of Philippine-claimed Scarborough Shoal, Manila filed a case with the Permanent Court of Arbitration at The Hague, questioning China's occupation of areas in the South China Sea that the Philippines considers its territory.

The court is expected to make a final decision in the next few months.

Song said the cause of the disputes in the South China Sea stemmed from the find of oil and gas deposits in the 1970s, when various countries occupied 42 islands and reefs that belonged to China by sending troops and cannons.

"China has the legal right and the capacity to retake these islands and reefs. Yet we refrained from doing so out of consideration for regional peace and stability," he said.

On Tuesday, the United States sent an Aegis destroyer within 12 nautical miles of Fiery Cross Reef in the contested Spratly Islands, where China has constructed an artificial island, to demonstrate that it does not recognize the area as Chinese territory by exercising what it calls freedom of navigation.

Song said navigation freedom applies to commercial but not military vessels.

"That country is flexing its muscle and making provocations in the South China Sea under the banner of freedom of navigation. Such actions pose a threat to China's sovereignty and security interests. We oppose such moves," he said, adding that bilateral negotiations between states directly concerned are the "only right approach" to address disputes.