Manila and Beijing traded accusations about a maritime confrontation Wednesday around the disputed Scarborough Shoal, a day after China submitted a chart of the South China Sea feature’s shore to the U.N. to bolster its claim over it.

China has blocked four Philippine vessels that attempted to “intrude into the territorial waters” of the disputed Scarborough Shoal on Wednesday, the country’s coastguard said.

People’s Liberation Army Navy warships and China Coast Guard cutters fired water canons and rammed a Philippine maritime patrol near Scarborough Shoal on Wednesday in the latest spat between the two countries in the South China Sea.