Photo: Collected

HONG KONG, April 8, 2026 (BSS/AFP) - Hong Kong activist Koo Sze-yiu, who is known for decades-long pro-democracy advocacy and street protests, died of cancer on Wednesday aged 80, a local advocacy group said.

A lifelong activist, Koo was among the handful of outspoken government critics remaining in the Chinese city after Beijing crushed Hong Kong's huge and sometimes violent democracy protests in 2019.

He was also involved in decades of protests over disputed islets in the East China Sea known as the Senkaku islands in Japan and the Diaoyu islands in China, and campaigned for Japan to apologise for its invasion of China during World War II.

Hong Kong-based group Action Committee for Defending the Diaoyu Islands said in a statement that Koo passed away in hospital, accompanied by his son.

Fellow pro-democracy activist Figo Chan said in a social media post that Koo was "a fighter who defends the Diaoyu Islands, cares about human rights activists in mainland China, and has repeatedly been jailed for the people, a fighter who truly loved his country."

Born in the Chinese city of Zhongshan in 1946, Koo spent most of his life in activism, from opposing the Portuguese colonial government in Macau to fiercely criticising Beijing's crackdown in Hong Kong.

He was diagnosed with terminal rectal cancer in 2020, but continued to actively participate in street campaigns even as Hong Kong's civil society has shrunk in recent years.

Koo was jailed at least 12 times since 2000, including a 2024 sentence for "attempted sedition" over plans to protest China's political clampdown with a prop coffin.

In 2022, he was jailed for the same offence over a planned protest against Beijing's Winter Olympics.

"I don't mind being a warrior for the democracy movement, and I don't mind being a martyr for democracy and human rights," he told a Hong Kong court at the time.