The Philippines has accused China of installing a “floating barrier” to stop fishing boats from entering a disputed area in the South China Sea.
The Philippines’ coast guard said the 300m (1,000ft) obstacle was preventing fishermen from working in a lagoon in the Scarborough Shoal.
China claims more than 90% of the South China Sea and seized the shoal in 2012.
Commodore Jay Tarriela of the Philippine coast guard said the barrier was discovered by a patrol on Friday.
Three Chinese coast guard boats and a Chinese maritime militia service boat installed the barrier when the Philippine vessel arrived, he said.
The Chinese boats issued 15 radio challenges and accused the Philippine ship and fishermen of violating international and China’s laws, before moving away “upon realising the presence of media personnel onboard the (Filipino) vessel”, he said.
China’s embassy in Manila did not immediately reply to a request for comment, Reuters news agency said.
Cmdr Tarriela of the Philippine coast guard said the said the barrier was “depriving [fishermen] of their livelihood”.
He added that Filipino fishermen say China typically installs such barriers when they monitor a large number of fishermen in the area.
He said his organisation would work with concerned governments but would “uphold our maritime rights and protect our maritime domains”.
The South China Sea is a rich fishing ground that is believed to hold vast oil and gas reserves. More than half of the world’s fishing vessels operate in this area.
China’s claims – which include sovereignty over land parcels and their adjacent waters – have angered not just the Philippines but also Vietnam, Taiwan, Malaysia and Brunei.
China has backed its expansive claims with island-building and naval patrols.
The US says it does not take sides in territorial disputes, but has sent military ships and planes near disputed islands in what it calls “freedom of navigation” operations.
Beijing seized the Scarborough Shoal in 2012 and forced fishermen from the Philippines to travel further for smaller catches.
It later allowed the Philippines to fish nearby when relations improved under former President Rodrigo Duterte.
However, tensions have heightened since Ferdinand Marcos Jr became president last year.
President Marcos Jr restored security ties with the US and in early 2023 granted American troops wider access to Philippine military bases.
This angered China as a larger US presence in the Philippines provides Washington with an arc of alliances stretching from South Korea and Japan to the north to Australia in the south.