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".