MANILA China’s actions in the South China Sea are "patently illegal", the Philippines’ defence secretary said on Monday, following a clash in disputed waters on Sunday over what Manila said was a resupply mission for fishermen.

"We have to expect these kinds of behaviour from China because this is a struggle. We have to be ready to anticipate and to get used to these kinds of acts of China, which are patently illegal as we have repeatedly said," Defense Secretary Gilberto Teodoro told reporters.

Manila’s South China Sea task force accused Chinese vessels of ramming and using water canons near Sabina shoal against a Philippine fisheries vessel transporting food, fuel and medicine for Filipino fishermen.

The Chinese coast guard said the Philippine vessel "ignored repeated serious warnings and deliberately approached and rammed" China’s law enforcement boat, resulting in a collision.

Asked if the latest incident would trigger treaty obligations between the United States and the Philippines, Teodoro said: "That is putting the cart before the horse. Let us deter an armed attack; that is the more important thing".

US officials including President Joe Biden have reaffirmed Washington’s "ironclad commitment" to aid the Philippines against armed attacks on its vessels and soldiers in the South China Sea.

"Everybody is too focused on armed attack; let’s make ourselves strong enough, so that does not happen," Teodoro said.

The Chinese embassy in Manila did not immediately respond to a request for comment. Monday is a public holiday in the Philippines.

The clash on Sunday had overshadowed efforts to rebuild trust and better manage disputes in the South China Sea, after months of confrontations.

China claims sovereignty over nearly all of the South China Sea, including areas claimed by the Philippines, Taiwan, Malaysia, Indonesia, Vietnam and Brunei.

An international arbitral tribunal in 2016 ruled that China’s claim had no basis under international law - a decision Beijing has rejected.

  - Reuters