Washington: Marking 33 years since the Tiananmen Square massacre, US Speaker House of Representatives Nancy Pelosi paid tribute to the brave Chinese demonstrators who inspired the world through what she described as one of the "greatest acts of political courage" in modern times.

"Today, the image of a lone figure - unyielding before a line of tanks - remains seared in the memory of all democracy-loving people. As the world honours the courage of students, workers and ordinary citizens who peacefully defied the Chinese Communist Party's oppressive regime, let us renew our vow to keep alive the flame of freedom that burned in their hearts," Pelosi said in a statement.

"From escalating aggression toward the Tibetan people to atrocities inflicted against Uyghurs and other Muslim minorities to crackdowns on the freedoms of peaceful activists and faith leaders, this regime's actions have shocked the conscience of the world," she added.

And as the world marks 25 years since the handover of Hong Kong, Pelosi pointed out how Beijing continues to defy the principle of 'one country, two systems' - imprisoning champions of freedom and the rule of law, including many of those who have kept alive the memory of Tiananmen for decades.

The Tiananmen Massacre was precipitated by the peaceful gatherings of students, workers, and others in Beijing's Tiananmen Square and other Chinese cities in April 1989, calling for freedom of expression, accountability, and an end to corruption. The government responded to the intensifying protests in late May 1989 by declaring martial law.

On June 3 and 4, the People's Liberation Army (PLA) soldiers fired upon and killed untold numbers of peaceful protesters and bystanders. In Beijing, some citizens attacked army convoys and burned vehicles in response to the military's violence.

The government has never accepted responsibility for the massacre or held any officials legally accountable for the killings.