Survivors of the 1989 massacre in Tiananmen Square have filed a civil lawsuit in New York against Mr Li Peng, the Chinese prime minister at the time, their lawyers announced.
Filed last Monday by four former student leaders arrested after the crackdown and by the brother of a student killed in Tiananmen Square, the suit was made public after it was served to Mr Li's security agents at a New York hotel on Thursday, lawyers said at a press conference.
Mr Li, who was out at the time, arrived in New York on Monday to attend the UN-sponsored Millennium Conference for Presiding Officers of National Parliaments.
The suit is based on US laws - specifically the 1992 Torture Victim Protection Act and the 1789 Alien Tort Claims Act - which allow victims of torture or human rights abuses anywhere in the world to demand reparations in US courts.
Judge William Pauley is to examine the suit, interview the plaintiffs, and decide whether it has merit.
"This lawsuit puts tyrants on notice," said Mr Xiao Qiang, executive director of the New York-based group, Human Rights in China. "They will be held accountable when they venture beyond the protection of their own fortress."
The trip is Mr Li's second to the United States since the military assault on student demonstrators in Tiananmen Square, in which hundreds, and perhaps thousands, of unarmed civilians were killed.
As prime minister in 1989, he issued the martial law order that opened the way for armed divisions of the People's Liberation Army to enter the city and fire on students and other citizens.
"My sister was killed in her 21st year," Mr Liming Zhang said "Today, I'm seeking Li Peng legal responsibility for the June 4th [1989] massacre. I'm seeking damages for the families of the victims. Eleven years have passed, and the government didn't even issued an apology."
Mr Feng Suo Zhou, a student leader who spent a year in jail before emigrating to the US, added: "This action is for us and for everyone who has fought in China for democracy and freedom. Justice is on our side, it's only a first step." Under the same law - the only one of its kind in the world - a Manhattan jury on August 10th ordered former Serb army leader Dr Radovan Karadzic to pay $745 million to women raped and tortured by his soldiers during the Bosnian war in 1992.
The first application of the law was the conviction of a Paraguayan police officer in 1980. A former Argentine general, the former Guatemalan minister of defence and a former Indonesian general have also been judged in US courts.
For the legal process to begin, the accused must be served with a lawsuit on US soil.