A free climber known as the "French Spiderman" scaled a Manila skyscraper on Tuesday to support the Philippines' maritime claims in the disputed South China Sea.

Frenchman Alain Robert, who has scaled more than 150 structures worldwide, including Dubai's Burj Kalifa and France's Eiffel Tower, drew a crowd and disrupted traffic in the Philippine capital's financial district.

He climbed the 47-storey GT Tower without a harness, and was promptly arrested after successfully descending from the skyscraper.

Robert said he climbed to raise awareness on the maritime disputes between the Philippines and China in the South China Sea.

"I know that there is tension, you know, with the Philippine Sea, and then just to remind people that the sea and the islands belongs to the Philippines and no one else, so that's the purpose of my ascent today," Robert said, without explaining why he was drawn to the cause.

Robert climbed the same skyscraper in 2019. He was arrested and fined 1,000 pesos ($18) for his stunt.

The Philippines accused China of "dangerous manoeuvres" on Tuesday that led to a collision between its coast guard ship and a Chinese vessel.

The incident was the latest in a series of maritime run-ins between the Philippines and China, which have been locked in a territorial dispute in the South China Sea despite a 2016 ruling by the Permanent Court of Arbitration which found that China's claims had no legal basis. Beijing rejects that ruling.

Manila financial district employee Andy Vergarra, who watched Robert's ascent, said his climb was "very frightening".

"Just watching him up there already makes me sweat. It's making me squeamish," Vergarra said.