A protester participates in a demonstration outside the Chinese Consulate in the financial district of Makati in Manila on Wednesday. (Aaron Favila/AP)

The Philippines protested a Chinese vessel hitting a Philippine fishing boat in disputed waters, a serious blip in the warming friendship between Philippine President Rodrigo Duterte and Beijing.

The boat, FB Gimber1, was anchored when it sank Sunday near Reed Bank in the South China Sea, a territory claimed by both countries. Its 22 crewmen were left at sea, but later saved by a passing vessel from Vietnam.

The Philippine Defense Department condemned “the cowardly action” by the Chinese vessel on Wednesday, just as the Philippines celebrated Independence Day.

“This is not the expected action from a responsible and friendly people,” Defense Secretary Delfin Lorenzana said.

Foreign Affairs Secretary Teddy Locsin announced in a tweet on Thursday that he filed a diplomatic protest.

Lt. Col. Stephen Penetrante, spokesman of the Armed Forces of the Philippines Command monitoring the area, said the military has reason to believe the incident was not an accident.

The collision tests Duterte’s embrace of Beijing, a major partner in his economic policy and infrastructure program. Since Duterte’s rise to power in 2016, his administration has dialed down on declaring protests to China’s increasing military presence in the area.

Duterte is best known for a bloody drug war that has left thousands dead, and a tough-talking demeanor that his supporters say prompted the United States’ return of pillaged war bells and Canada’s recent acceptance of tons of garbage shipped to the Philippines in 2013.

But the president has been observed to be less firm with China, repeatedly stressing that the Philippines cannot afford a war over the maritime dispute. Critics believe Duterte’s approach is easing the territory right into Beijing’s hands.

Jay Batongbacal, director of the University of the Philippines’ Institute for Maritime Affairs and Law of the Sea, said the incident shows that Duterte cannot bank on his personal rapport with Chinese President Xi Jinping.

“It only goes to show that despite this friendship, . . . China’s behavior has not really changed,” he said. “It might be said that China is now abusing the government's inaction. ... that’s why something like this could happen, so close to our shores, against our own citizens.”

Presidential spokesman Salvador Panelo called on Chinese authorities Thursday to impose sanctions on those involved, but did not remark on whether the collision was intentional. He called the collision a “crystal clear violation of maritime protocol.”

A protester holds up a sign outside the Chinese Consulate in Manila on Wednesday. (Aaron Favila/AP)

“Regardless of the nature of the collision, whether it was accidental or intentional, common decency and the dictates of humanity require the immediate saving of the crew of the downed Philippine vessel,” Panelo said in a statement.

The Chinese Embassy in Manila did not immediately respond.

The Permanent Court of Arbitration in The Hague ruled that the disputed territory in the South China Sea was covered by the Philippines’ sovereign rights. China has refused to recognize the decision.

Former government officials filed a complaint against Xi at the International Criminal Court this year. They accused China of destroying marine areas in the disputed waters, a move that affects the livelihoods of fishermen there.

Batongbacal said the collision should be a “wake-up call” for changes in Duterte’s policy.

“If the action taken by China on this incident is unsatisfactory — if they ignore or downplay it — we can expect it will be repeated in the future,” he said. “Or that China will further abuse the friendship the Philippines has shown to it.”