Bao Tong, the most senior Communist Party official imprisoned over the Tiananmen protests that shook Beijing in 1989, has died at 90.

But even as Chinese activists the world over mourn his passing, the news has drawn no reaction in his own country, where the internet is heavily censored.

Bao championed political reform in the 1980s during pro-democracy protests. But after crushing the movement, the Communist Party expelled Bao and jailed him for seven years.

In the years that followed, the historic protests at Tiananmen effectively disappeared from public record - and so did all mention of the massacre, whose exact toll still remains unknown.

Even today, a search for Bao's name on Weibo, China's heavily censored version of Twitter, yields no results. The screen says they cannot be displayed because of "relevant law and regulations".

As a result of the Communist Party's harsh crackdown on any topic related to the 1980s protests, or any other form of dissent, few young Chinese know Bao's name.

But condolences poured in from everywhere else after his son Bao Pu confirmed his death, saying his father had died peacefully on Wednesday morning in Beijing, the city he had called home for decades.

"It doesn't matter whether I reach 90, what's important is the future we all should fight for... we should do what we are supposed to do, then we'll realise our value, the value of our life."