In June 1989, students and workers occupied Beijing's Tiananmen Square for a huge pro-democracy protest.
Chinese army troops brutally suppressed the peaceful protests and killed and wounded thousands of people.
To mark the six weeks of demonstrations in the Beijing massacre, vigils and events are being held in Hong Kong, London, Washington DC and other cities around the world.
CSW said in a statement that it "joins organisations and individuals around the world in remembering once more the brutal and tragic events of that time".
The Christian Charity also said: "We stand with the surviving family members of the victims, who, three decades on, are still seeking justice and truth.
"We commend their courage and their determination, at the same time as we condemn the authorities' forceful suppression of their rights.
"Under President Xi Jinping there has been a pattern of increasing human rights abuses: a stranglehold over civil society; a heightened sensitivity to perceived challenges to Party rule; and the introduction of legislation that curtails civil and political rights in the name of national security.
"There has also been a rapid and alarming decrease in freedom of religion or belief, marked by the closure of thousands of temples, churches and mosques, the detention and disappearance of religious leaders, and the stripping away of religious symbols and signs."
Stay up to date with the latest news stories from a Christian perspective. Sign up to our daily newsletter and receive more stories like this straight to your inbox every morning.
