Tensions have flared in the South China Sea after a Chinese fishing vessel collided with a Filipino boat and left 22 men on board to drown.
The 22 Filipino men were left floating at sea before they were rescued by a Vietnamese boat, sparking fury from President Rodrigo Duterte.
Mr Duterte, who has sought closer ties to with Beijing since his rise to power, was "outraged" over the "hit-and-run" incident, according to the South China Morning Post.
"We will not allow ourselves to be assaulted, to be bullied, to be the subject of such barbaric, uncivilised and outrageous actions," presidential spokesman Salvador Panelo said. "Whether it's a form of bullying or not, it's outrageous, it's barbaric, it's uncivilised, and we're condemning it."
Mr Panelo said that if the incident was deliberate, it would be considered an "act of aggression".
He also noted that the Philippines would consider cutting diplomatic ties with China.
But it seems the country will not be looking to the United States for support, with foreign affairs secretary Teodoro Locsin Jr tweeting: "F*ck the international community. This is our fight and in the end ours alone."
Another opposition senator, Risa Hontiveros, called on Mr Duterte to recall the Philippine ambassador and consuls in China to pressure Beijing to identify and punish the Chinese crewmen allegedly involved in the incident.
China condemned the incident but did not immediately confirm or deny that a Chinese vessel was involved.
The long-contested South China Sea has long been seen as a potential flash point in Asian relations.
Tensions escalated after China converted seven disputed reefs into islands which can serve as forward military bases and intimidate rival claimant states in the strategic waterway, where US forces undertake "freedom of navigation" patrols.
In Beijing, Chinese foreign ministry spokesman Geng Shuang said the incident "should be condemned" wherever the vessel came from.
Citing information provided by the Philippines, Mr Geng described the sinking as "an ordinary maritime traffic accident" and criticised assumptions made about it.
"It is irresponsible to resort to the media to hype and politicise the incident without verification," he said, adding a Chinese investigation was underway in co-ordination with Philippine authorities.
The Philippine coast guard said it was checking whether those involved were Chinese fishermen or from other neighbouring countries such as Vietnam and if the collision was intentional.