Philippines fishermen have thrown firebombs at Chinese law enforcement vessels in the South China Sea, reportedly in retaliation to being struck by bottles hurled from China's coastguard ships.
Reports say a clash occurred at Scarborough Shoal, an area China seized control of after a three-month stand-off with the Philippines coastguard in 2012.
China's Foreign Ministry said Scarborough Shoal - known by Beijing as Huangyan Island - was Chinese territory which Philippines fishermen had been fishing around illegally.
A spokeswoman said Chinese ships advised the trawlers to leave, in accordance with the law, but they refused to obey.
She said China had strengthened its "management" around the shoal, without elaborating.
