The Philippine Coast Guard on Monday accused a Chinese coastguard vessel of shining a "military-grade laser light" at one of its boats in the disputed South China Sea, temporarily blinding crew members.
The incident happened on 6 February nearly 20 kilometres (12 miles) from Second Thomas Shoal in the Spratly Islands, where Philippine marines are stationed, the coast guard said in a statement.
It was the latest episode in a series of maritime incidents between the Philippines and China, which claims sovereignty over almost the entire South China Sea and has ignored an international court ruling that its claims have no legal basis.
The incident also occurred days after the United States and the Philippines agreed to resume joint patrols in the sea and struck a deal to give US troops access to another four military bases in the Southeast Asian country.
The Philippine patrol boat was supporting a "rotation and resupply mission" last week for the troops, who live in a derelict navy ship grounded on the shoal to assert Manila's territorial claims.
The Chinese Coast Guard vessel shone a "military-grade" green laser light twice at the Philippine ship, "causing temporary blindness to her crew at the bridge", the statement said.
The Chinese vessel also made "dangerous maneuvers" by coming within about 140 metres of the Philippine boat.
"The deliberate blocking of the Philippine government ships to deliver food and supplies to our military personnel... is a blatant disregard for, and a clear violation of, Philippine sovereign rights in this part of the West Philippine Sea," the Philippine Coast Guard said.
Manila refers to waters immediately to its west as the West Philippine Sea.
It is not clear if the resupply mission to Second Thomas Shoal was successful. Privately owned vessels are normally used to carry supplies, with the coast guard accompanying them.
The Chinese embassy in Manila did not respond immediately to a request for comment.
Chinese coast guard and maritime militia vessels also blockaded the Philippines-garrisoned shoal in August to stop government ships from reaching the troops, the coast guard said.
Philippine President Ferdinand Marcos and his Chinese counterpart Xi Jinping agreed in January to set up direct communication between their foreign ministries to avoid "miscommunication" in the area.
It is not known if the hotline was used in the latest incident.
The US-Philippine deal earlier this month brings to nine the total number of Philippine bases accessible to US forces.
It comes as the long-time allies seek to counter China's military rise in the region.
Vietnam, Malaysia and Brunei also have overlapping claims to parts of the South China Sea.