China Tuesday renewed calls for the Philippines to remove an ageing ship from a reef which Manila uses to press its stake in the Spratly Islands in defiance of Beijing's claim to nearly the entire South China Sea.

The move comes after the Philippines at the weekend accused the China Coast Guard of firing water cannon against boats on a resupply mission to its garrison stationed on the grounded vessel.

The BRP Sierra Madre -- deliberately grounded in the late 1990s in an effort to check the advance of China in the hotly contested waters -- has long been a flashpoint between Manila and Beijing.

The handful of Philippine marines deployed on the crumbling vessel depend upon resupply missions to survive their remote posting.

The Philippine military and coast guard accused the China Coast Guard of breaking international law by blocking and firing water cannon at the resupply mission, preventing one of the charter boats from reaching the shoal.

Beijing has defended its actions as "professional" and accused Manila of "illegal delivery of construction materials" to the grounded ship.

"The Philippine side has repeatedly made clear promises to tow away the warship illegally 'stranded' on the reef," a spokesperson for China's foreign ministry said Tuesday.

"Twenty-four years have passed, the Philippine side has not only failed to tow away the warship, but also attempted to repair and reinforce it on a large scale to achieve permanent occupation of the Ren'ai Reef," they added, using the Chinese term for the Second Thomas Shoal.

"The Chinese side once again urges the Philippines to immediately tow away the 'stranded' warship from the Ren'ai Reef and restore the status of no one and no facilities on the reef," they said.

- 'Illegal activities' -

Second Thomas Shoal is about 200 kilometres (120 miles) from the Philippine island of Palawan and more than 1,000 kilometres from China's nearest major landmass, Hainan island.

China's coast guard and navy vessels routinely block or shadow Philippine ships patrolling the contested waters, Manila says. 

The Philippines has issued more than 400 diplomatic protests to Beijing since 2020 over its "illegal activities" in the South China Sea, the foreign ministry said.

China appeared to be "trying to gauge our commitment to supply our troops" at the shoal, National Security Council spokesman Jonathan Malaya told reporters on Monday.

"For the record, we will never abandon Ayungin Shoal," Malaya added, using the Philippine name for Second Thomas Shoal.

Saturday's "David and Goliath" incident showed the Chinese had established what appeared to be a "blockade" of the shoal, Malaya said.

Manila and Beijing have a long history of maritime disputes over the South China Sea but former Philippine president Rodrigo Duterte was seen as cosying up to China in the hope of attracting investment.

Since succeeding Duterte, President Ferdinand Marcos has insisted he will not let China trample on his country's maritime rights, seeking to strengthen defence ties with former colonial ruler and longtime ally the United States.

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