The Philippines on Wednesday denounced the crew of a Chinese fishing boat that collided with a Philippine vessel and left 22 Filipino fishermen abandoned in the disputed South China Sea.

The collision took place near the Reed Bank on Sunday, the defence ministry said, adding that a Vietnamese fishing boat rescued all the fishermen.

“We denounce the actions of the Chinese fishing vessel for immediately leaving the incident scene, abandoning the 22 Filipino crewmen to the mercy of the elements,” Defence Secretary Delfin Lorenzana said in a statement.

Reuters could not independently verify the Philippine account of the collision.

In Beijing on Thursday, foreign ministry spokesman Geng Shuang said it was an “ordinary maritime accident” and he warned against “irresponsibly politicising” the collision.

He said China is investigating the incident.

China, which claims nearly all of the South China Sea, has been accused of using thousands of fishing boats as a militia and de facto extension of its foreign policy.

The Reed Bank contains offshore gas reserves that both countries claim ownership of, despite it being located within the Philippines’ 200-nautical mile exclusive economic zone.

Both countries say they are seeking ways to jointly tap those deposits.

Despite a long history of rows with China over the South China Sea, Philippine President Rodrigo Duterte has pursued warmer ties with Beijing in exchange for billions of pledged loans and investment.

An international arbitration panel in 2016 ruled the Philippines had sovereign rights to exploit the resources at Reed Bank. China did not recognise the case or the verdict.