The Philippines has formally sought international arbitration against China’s territorial claims on territories in the potentially resource-rich waters of the South China Sea.

Foreign Secretary Albert del Rosario told a news conference on Tuesday that Manila had notified Beijing of the move through a note verbale delivered to the Chinese ambassador to Manila, the Financial Times reports.

“The Philippines has exhausted almost all political and diplomatic avenues for a peaceful negotiated settlement of its maritime disputes with China,” del Rosario said. “To this day, a solution is still elusive”.

The Philippines will bring both countries’ conflicting claims over the territories to a tribunal of the UN Convention on the Law of the Sea in hopes that it would rule against China’s vast claim in the South China Sea.

Manila hopes the tribunal would order China to “desist from activities that violate the rights of the Philippines in its maritime domain,” del Rosario said.

Still, no arbitration will proceed unless both parties approve it. China would unlikely agree to such a process, underlining its previous stance on settling the dispute through negotiation between the parties, according to Al Jazeera.

The Chinese embassy did not comment directly but reiterated that “China has indisputable sovereignty over the islands in the South China Sea and its adjacent waters,” Chinese ambassador to the Philippines Ma Keqing said.

The move by the Philippines marks the first time any of the parties with overlapping claims has initiated to resolve the dispute through legal action, the FT reports.