Chinese Coast Guard vessels and Philippine ships collided with each other amid mounting tensions in a contested area of the South China Sea on Sunday.

The Armed Forces of the Philippines said in a statement that two minor collisions occurred during a routine resupply mission to the Second Thomas Shoal in the disputed Spratly Islands on October 22.

It said China Coast Guard vessel 5203 collided with the Philippine resupply boat Unaiza May 2, while the Chinese Maritime Militia vessel 00003 bumped into the port side of Philippine Coast Guard vessel MRRV 4409 during the same mission.

The Chinese Coast Guard said it 'lawfully blocked' the Philippine ships transporting 'illegal construction materials' to the BRP Sierra Madre, a World War II-era vessel turned military outpost intentionally grounded by the Philippines to lay claim to the shoal back in 1999.

Philippine authorities have denounced the 'dangerous blocking maneuvers' which they said imperiled the safety of the crew involved. They said despite the incidents, the resupply mission was a success.

Western countries including the U.S., Canada, and France, have also raised concerns over the collisions.

The incident is the latest in a series of tense maritime confrontations between the Philippines and China in this area of the South China Sea.

China currently lays claim over almost the entire South China Sea, one of the world's busiest sea lanes. But a United Nations-backed tribunal in 2016 deemed its claims groundless.