MANILA, Philippines (AP) — The Philippines protested on Thursday China’s designation of a disputed South China Sea reef, which it has turned into a heavily fortified island base, as a Chinese “administrative center.”

The Department of Foreign Affairs issued a statement objecting to what it called China’s “illegal designation” of Fiery Cross Reef as a regional administrative center in the hotly contested Spratly archipelago.

It’s the latest in a series of disagreements in the sea as Asian nations grapple with the coronavirus pandemic. U.S. Secretary of State Mike Pompeo accused China last week of taking advantage of widespread distraction over the pandemic to advance its territorial claims.

“The Philippines calls on China to adhere to international law,” the department said, reminding Beijing of a 2002 agreement that urged governments with rival claims in the sea to exercise self-restraint and avoid actions that would escalate the disputes and undermine regional stability.

The Philippine government has protested China’s self-declared territorial zones in the waters starting in 2012, with what it said was Beijing’s “unlawful establishment” of a Sansha City covering much of the South China Sea. It said it “does not recognize Sansha nor its constituent units nor any subsequent acts emanating from them.”

The Department of Foreign Affairs cited a July 2016 international arbitration ruling that invalidated China’s sweeping territorial claims in the South China Sea on historical grounds. China refused to participate in the arbitration case, which was initiated by the Philippines, and refused to recognize the ruling.

Last week, the Philippines protested China’s establishment of two districts to administer two disputed groups of islands and reefs in the South China Sea.

One district reportedly covers the Paracel islands and the other has jurisdiction over the Spratlys, where China has turned seven reefs, including Fiery Cross, into missile-protected island bases, including three with runways.

The Philippines has a presence on at least nine islands and islets in an area it claims in the Spratlys.

The U.S.-based Asia Maritime Transparency Initiative, which monitors the territorial conflicts, said Fiery Cross has been developed into one of China's most advanced island bases in the waters with missile shelters, structures with retractable roofs, radars and a runway.

The Philippines also lodged a protest last week over a Chinese navy ship’s aiming of its weapons control radar at a Philippine navy ship in mid-February. The radar locks weapons on a target prior to an actual attack, although the Chinese navy ship did not fire.

China and the Philippines, along with Vietnam, Malaysia, Brunei and Taiwan, have been locked for decades in an increasingly tense conflict over mostly barren islands, reefs and atolls and rich fishing waters in the South China Sea.