MANILA – The Philippines has accused Chinese coast guard ships and a Chinese navy helicopter of harassing Philippine fisheries vessels conducting a scientific survey in a disputed area of the South China Sea, forcing the operation's cancellation, according to statements from the Philippine coast guard on Saturday.

The incident reportedly occurred on Friday near Sandy Cay, a group of three small sandbars located between an artificial island base controlled by Chinese forces and a Philippines-occupied island within the Spratly archipelago.

Video footage released by the Philippine coast guard purportedly shows one of the Chinese coast guard ships sailing in close proximity to a Philippine vessel, while another clip depicts a Chinese military helicopter flying low over the seas close to a vessel flying the Philippine flag.

There has been no immediate reaction from Chinese officials regarding the incident, which adds to existing tensions in the South China Sea—a highly strategic maritime route used for international trade and security.

China maintains claims over a large portion of the South China Sea, demarcated by a 'ten-dash line' in its maps, although the exact coordinates have not been fully delineated.

This area is also claimed in parts by several other nations, including the Philippines, Vietnam, and Malaysia.

The friction over territorial claims in these waters occurs amid ongoing scrutiny of China's assertive military posture in the region.

The event may also pose a test to the current policy stance of the United States under President Donald Trump, who has pledged to counterbalance China's actions in these disputed waters.

His predecessor, Joe Biden, had previously worked on reinforcing alliances in Asia aimed at checking China’s activities in the South China Sea as well as in the East China Sea and around Taiwan.

U.S. Secretary of State Marco Rubio, in a telephone conversation with Philippines Foreign Secretary Enrique Manalo, discussed various issues, including the recent actions by China in the South China Sea.

According to State Department spokesperson Tammy Bruce, Rubio criticized China's conduct in the area as destabilizing and unlawful, affirming the United States' commitments under the mutual defense treaty with the Philippines, which remains America's oldest treaty ally in Asia.

The Biden administration had warned China of the United States' obligations to assist in defending the Philippines if its forces were to come under attack, including in the contested areas of the South China Sea.

In response, China has consistently cautioned the U.S. to refrain from involving itself in disputes it characterizes as purely regional.