BEIJING — China has published benchmarks for a contested shoal in the South China Sea seized from the Philippines, a move that could heighten tensions over overlapping territorial claims.

The Foreign Office posted online the geographic coordinates for the baselines around Scarborough Shoal on Sunday. A nation’s territorial waters and exclusive economic zone are usually defined as the distance from the baselines.

Both China and the Philippines claim Scarborough Shoal and other outcrops South China Sea. China seized the shoal, which lies west of the main Philippine island of Luzon, in 2012 and has since restricted access to Filipino fishermen there. A 2016 ruling by an international arbitration court found most of China’s claims in the South China Sea to be invalid, but Beijing refuses to comply.

Ships from China and the Philippines have collided several times as part of increased clashes, and the Chinese coast guard has fired water cannons at Philippine ships.

China’s move came two days after Philippine President Ferdinand Marcos Jr. signed two laws the delimitation of the government’s claims in the disputed waters.

A statement from the Chinese Foreign Ministry said the delimitation of the baselines was in accordance with a UN agreement and Chinese law.

“This is a natural step by the Chinese government to legally strengthen maritime management and is in line with international law and common practices,” the statement said.

The statement added that one of the laws signed by Marcos, the Philippine Maritime Zones Act, violates China’s sovereignty in the South China Sea.

“China firmly opposes and will continue to do everything necessary in accordance with the law to firmly defend its territorial sovereignty and maritime rights and interests,” the Foreign Ministry said.

China stakes claim to almost all of the South China Sea. It has a series of disputes with several Southeast Asian nations, including the Philippines and Vietnam, over territories in the waters, which are part of a key shipping route in Asia.