The Philippines said a Chinese Navy chopper harassed Filipino fishing boats at a disputed South China Sea reef, showing lingering tensions in the key waterway.

China’s coast guard said on Monday that it had taken “necessary control measures” against an “illegal gathering” of Philippine vessels in disputed waters of the Iroquois reef in the South China Sea. A number of Philippine ships have in recent days “illegally” gathered in the waters of the reef in the Spratly Islands under the banner of