Liu Dejun, a spokesman for the Chinese coastguard, said two Philippine reconnaissance aircraft had “illegally entered Chinese air space above Huangyan Island” (the Chinese name for Scarborough Shoal).

He added that the planes had been expelled in “accordance with laws and regulations”.

The previous day the Philippines said another one of its planes had been “subjected to aggressive interference” during a routine maritime domain awareness flight over the reef.

Jay Tarriela, a spokesman for the Philippine coastguard, shared pictures on social media of a Chinese helicopter and a video of a J-16 fighter jet which, he said, had been “harassing” and “endangering” its aircraft.

“Such actions pose a clear and unacceptable risk to the safety of [coastguard] personnel and the journalists embedded on the mission,” Tarriela said.

He added that Philippine coastguards had also spotted two buoys on the reef on Tuesday and Wednesday, as well as debris from previous construction work “dating back at least two years”.