In the spring of 1989, more than one million people protested in the square, camping out

to demand freedom and change.

The movement was sparked by the death of Communist Party leader Hu Yaobang, who had been removed

from office by party hardliners - subsequently becoming an icon for democratic reform.

Chinese troops opened fire on the pro-democracy demonstrators after they were ordered by the

military to enforce martial law in the country's capital.

The footage of a lone protester standing in front of a line of tanks - known now as "Tank

Man" has become one of the most powerful symbols of the 20th Century.

The man carrying two plastic bags, one in each hand, is seen standing directly in the

path of a column of armored tanks, effectively preventing them from moving down the avenue

towards the square.

Protesters did not attack or provoke the soldiers, but the military fired at them anyway.

The attack continued until June 5th.

During that period of time, tanks were sent out and they showed no mercy to the protesters.

Today's anniversary, also known as the June Fourth incident, has never been publicly marked

in mainland China.

But every year there are public commemorations in Hong Kong.

On 26th April this year a museum dedicated to the brutal 1989 crackdown opened in Hong

Kong despite a small group of pro-China protesters questioning its version of the truth.

Exhibits include video footage and newspaper articles from 25 years ago.

In a simple opening ceremony, the museum's founders tore apart a copy of a 1989 editorial

from the government mouthpiece newspaper People's Daily to reveal the logo of the museum.

Jonathan Chan, a Hong Kong resident, was a student when he flew to Beijing to show support

for the movement. He can vividly remember scenes from that day.

It was on the lobby, it was on the wall, all the blood spilled from the wounded people.

And...

People crying for help, moaning for their pain. It's unbearable.

Freedom is modern China, one of the most economically powerful nations in the world, remains a divisive

issue.

Ahead of the Olympics in 2008, there was unrest in Tibet with a series of riots and protests.

According to the Chinese administration governing Tibet, the unrest was motivated by separatism

and orchestrated by the Dalai Lama.

The spiritual leader of Tibet said he did not encourage the protests.

China's pledge to the world that the international media would be allowed to report freely during

the Beijing Games appeared broken after a British reporter was briefly detained by Chinese

police while covering a Free Tibet protest.

I've been arrested. These people have arrested me. I've been arrested by the Chinese police

for just trying to cover the protest here. I was inside the car...

ITV News's John Ray was forcibly removed along with demonstrators but was released shortly

afterwards.

Wrestled me up here, and they've taken my shoes off me. They've taken my equipment back.

They've taken all the equipment I've got, and they won't tell me why I've been arrested.

Are you arresting me? I want to talk.

In more recent weeks, China has rebuked the United States for calling for the release

of activists, including lawyers, professors and journalists, detained after attending

a meeting about the 1989 Tiananmen Square protests, saying Washington had no right to

demand criminals be set free.

The Chinese Foreign Ministry has also urged Vietnam to immediately stop what it says are

provocative and sabotaging actions against China's oil-drilling operation in the South

China Sea, and warned Japan to stay out of it.

Last week saw thousands of people queuing a subway station in Beijing to pass security

checks which have been tightened following a series of bloody attacks in China's troubled

western Xinjiang region.