​China is against the Philippine Senate's passing of the Maritime Zones Act as it said the measure will only advance the enforcement of what it claims as illegal arbitral award on the South China Sea.

Mao Ning, China's Foreign Ministry spokesperson, said Tuesday that the Philippines is attempting "to put a legal veneer on its illegal claims and actions in the South China Sea" under the pretext of the United Nations Convention on the Law of the Sea (UNCLOS).

Mao said such a measure "goes against the provisions of international law, including the UN Charter and UNCLOS, and against the spirit of the Declaration on the Conduct of Parties in the South China Sea."

She did not particularly cite which provision of the UNCLOS the Philippines may have "go(ne) against."

"This completely horrendous act will inevitably make the situation in the South China Sea more complex," Mao claimed.

Mao made the remark during her Tuesday's briefing following the Senate's approval of the Philippine Maritime Zones Act, which will set archipelagic boundaries in compliance with UNCLOS and the 2016 The Hague arbitral ruling.

"China firmly opposes it and has lodged solemn démarches to the Philippines," she said.

Mao also raised several points to reaffirm China's position over the West Philippine Sea

She said China's claim over the waters has been established "in the long course of history" and is supposedly in compliance with the UN Charter and UNCLOS.

She also claimed Scarborough Shoal and the Spratly Islands are also beyond the limits of Philippine territory.

Mao said the Philippines is unilaterally initiating an international arbitration without China's supposed consent.

The 2016 Arbitral Award, which Mao was referring to, came up following an arbitral case that Manila filed against Beijing, which China refused to participate in.

"The arbitral tribunal in the South China Sea arbitration handled the case ultra vires and made an illegitimate ruling. The rendered award is illegal, null and void. China neither accepts nor participates in that arbitration, neither accepts nor recognizes the award, and will never accept any claim or action arising from the award," Mao said.

Mao then said China is urging the Philippines to respect China's claim over the West Philippine Sea, tagging it as their "territorial sovereignty and maritime rights and interests."

She said the Philippines must "immediately end any unilateral move that may escalate the dispute and complicate the situation, return to the right track of properly settling differences through negotiation and consultation as soon as possible and work with China to uphold the larger interest of the bilateral relations and keep the South China Sea peaceful and stable."