Vice President Leni Robredo speaks before the ASEAN Business and Investments Summit in Parañaque City, November 2017. Mark Demayo, ABS-CBN News

MANILA - Vice President Leni Robredo on Sunday hit China's reported installation of new missiles on artificial islands in the West Philippine Sea.

US network CNBC reported Wednesday that the Chinese military installed anti-ship and air-to-air defenses on outposts also claimed by Vietnam and the Philippines over the last 30 days, citing sources close to US intelligence.

"The increased militarization is in violation of UNCLOS (United Nations Convention on the Law of the Sea) and serves to contribute to regional instability, compromise our security, and further curtail our sovereignty," Robredo said in a statement.

The West Philippine Sea, she noted, is a major passageway for ships from different countries conducting trade around the world.

"Heightened tensions in the area will be to the detriment of all parties concerned... This area should continue to serve as an open waterway for all countries, in accordance to international laws," she said.

The Vice President urged the administration to "take immediate and appropriate actions, including the filing of a diplomatic protest, to protect what is rightfully owned by the Filipino people."

Chinese foreign ministry spokeswoman Hua Chunying has neither confirmed nor denied the deployment of missiles in the waterway.

"China's peaceful construction in the Spratly archipelago, including the deployment of necessary national defense facilities, is aimed at protecting China's sovereignty and security," she said.

"Those who don't intend to violate (this sovereignty) have no reason to worry," she said.

The South China Sea issue has been brewing for years, with China, the Philippines, Brunei, Malaysia and Vietnam making competing claims in waters with vital global shipping routes and what are believed to be significant oil and natural gas deposits.

In addition to land-reclamation efforts on reefs it controls and building civilian facilities there, China also has air bases, radar and communications systems, naval facilities and defensive weaponry in place including landing strips able to accommodate military planes.

The new Chinese missiles were reportedly deployed on Fiery Cross Reef, Subi Reef and Mischief Reef, according to CNBC.

They are all in the Spratly archipelago located in waters south of mainland China between Vietnam and the Philippines.

Malacañang had said it was "concerned" with the China’s reported actions in the area, but said it was "confident that those missiles are not directed at us."

With a report from Agence France-Presse