A Philippine civilian convoy set sail on Wednesday for a shoal and fishing ground in the South China Sea to assert Manila's claim to the Beijing-controlled area, with activists accusing Chinese boats of interfering with their voyage.

The fleet of four fishing boats, carrying about 100 people including journalists, departed Luzon island in the demonstration dubbed "Atin Ito," meaning "This is ours" in Tagalog, escorted by a Philippine Coast Guard ship.

People install navigation buoys as a sign of Philippine sovereignty over the waters off Zambales province in the country's north on May 15, 2024. (Photo courtesy of the civic group "Atin Ito") (Kyodo)

Rafaela David, the leader of the activists, said earlier that their objective was not to "incite conflict" with China, but rather to reclaim "what rightfully belongs to us."

After they traveled some 80 kilometers, at least two Chinese Coast Guard ships began shadowing and blocking the civilian vessels just before nightfall, the Philippine Coast Guard and activists said separately.

Beijing has controlled the shoal since a standoff with the Southeast Asian country in 2012.

"They are trying to divide the contingent. Our boats are exercising evasive maneuvers," Emman Hizon, the protest's spokesperson, said of the moves by the Chinese vessels.

He said the escorting Philippine vessel also received "radio challenges" from one of the Chinese ships.

A Philippine Coast Guard airplane earlier in the day observed dozens of Chinese vessels and floating barriers installed near the Scarborough Shoal, which is about 200 km from the island.

Adm. Ronnie Gavan, commandant of the Philippine Coast Guard, told Kyodo News, "We will make sure that there will be no harsh interference that will happen along the way, and to guide them through if there's a need to."

Hizon said the group is determined to complete the three-day sail and distribute food and fuel to Philippine fishermen along the way. The activists have also installed navigation buoys as a sign of protest against China.

In ongoing disputes with the Philippines and other Southeast Asian countries, China asserts sovereignty over many parts of the sea even after the Permanent Court of Arbitration at the Hague invalidated such a claim in a 2016 ruling.

Since last year, run-ins between patrolling Philippine government boats and Chinese vessels have become more frequent and heated. The latest occurred on April 30, when Chinese ships fired water cannons at Philippine boats near Scarborough.

The activists launched a similar action off the Philippines' Palawan island in December, but the trip was aborted after Chinese vessels interfered.

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