MANILA (UPDATED) - President Rodrigo Duterte said Monday he would not waver in defending the Philippines' interests, despite seeking closer ties between Manila and Beijing.

"Our improved relationship with China does not mean we will waver to defend our interest in the West Philippine Sea," Duterte said in his third State of the Nation Address.

The Philippines continues to "engage" China through bilateral and multilateral channels, he said.

“Opening lines of communication and amicably managing differences have led to positive developments that include renewed access of Filipino fishermen in the areas in dispute in the Philippines — West Philippine Sea,” he said.

Duterte has refused to flaunt the Philippines victory against China in a United Nations-backed arbitration court in 2016, instead seeking closer diplomatic and trade ties with the world’s second largest economy.

Duterte's predecessor, former President Benigno "Noynoy" Aquino, initiated the case against China but the ruling was handed down less than a month after the incumbent assumed power.

Since assuming the presidency, Duterte has looked to China for funding of the government’s infrastructure projects.

Duterte has argued that the Philippines cannot match China’s military and economic might, adopting instead a friendly policy that observers say has hurt Manila’s ties with traditional ally Washington.

But the President appears to have failed to harness his popularity in shifting public opinion towards China, as majority of Filipinos apparently wanted Manila to assert its claim in the resource-rich sea, according to various polls.

A Pulse Asia poll conducted from June 15 to 21 this year revealed that 73 percent of Filipinos believe that President Rodrigo Duterte should assert Manila's rights to the West Philippine Sea, the country's exclusive economic zone within the contested waters.

• Majority of Filipinos want Duterte to assert sovereignty in West PH Sea: poll

Meanwhile, a Social Weather Stations survey revealed that 4 out of 5 Filipinos think it’s wrong that the government is “leaving China alone with its infrastructures and military presence” in its own territories.

• 4 out of 5 Pinoys want gov’t to act on China’s militarization in disputed waters: survey

The SWS survey also showed China's trust rating among Filipinos declined by 42 points to -35 in the second quarter from +7 in March 2018.

The survey found 53 percent of Filipinos have little trust in China, while 18 percent have much trust, and 27 percent were undecided.

This is the lowest since the "bad" -37 in April 2016, SWS said.

China also drew flak after its coastguard personnel were found to be harassing fishermen in Scarborough Shoal, a traditional fishing ground located only 124 nautical miles off Zambales.

• China still rules over Scarborough Shoal, say Filipino fishermen