BEIJING — The Permanent Court of Arbitration in The Hague said on Wednesday that it would announce its rulings in a contentious case between China and the Philippines over the South China Sea on July 12.

The landmark case centers on the Philippine government’s argument that China’s claims over much of the sea, a strategic waterway in the western Pacific, are illegal under the United Nations Convention on the Law of the Sea. The Philippines initiated the case in 2013 after China seized Scarborough Shoal, an atoll that the Philippines administered and that was a favorite fishing ground for Filipino fishermen.

A special five-member tribunal established by the court in 2013 will also decide on the size of maritime zones around rocks and reefs in the Spratly archipelago off the Philippine coast. It will also rule on whether China has caused environmental damage in constructing an artificial island at Mischief Reef.

China has refused to participate in the proceedings, saying that the tribunal has no jurisdiction, and has insisted that it will ignore its rulings.