At least two personnel on the Philippine vessel near the Second Thomas Shoal were carrying guns on deck, pointing them in the direction of China's Coast Guard, CCTV said in a social media post.

An accompanying 29-second video appeared to show a masked man momentarily holding up a blurred black object that resembled a rifle.

China claims almost the entire South China Sea, a conduit for more than $3 trillion of annual ship-borne commerce, including parts claimed by the Philippines, Vietnam, Indonesia, Malaysia and Brunei. The Permanent Court of Arbitration in 2016 said China's claims had no legal basis.

CCTV said the alleged incident occurred during a Philippine mission to supply troops. The troops are stationed on a rusting warship that Manila grounded in 1999 to reinforce its sovereignty claims.

The Philippine navy, coast guard and National Security Council, as well as the country's embassy in Beijing did not immediately respond to requests for comment.

Philippine President Ferdinand Marcos Jr, in a speech on Friday attended by China's defence minister, made a thinly veiled reference to Beijing, denouncing what he called illegal, coercive and aggressive actions in the South China Sea, which were undermining Southeast Asian countries' a vision for "peace, stability and prosperity" in the sea.

Confrontations between the Philippines and China in the South China Sea have grown more tense and frequent during the past year, including China's Coast Guard using water cannons and accusations by Manila that it had rammed Philippine vessels.