It blamed the IOC for failing to put more pressure on China and for "sending a message that it is acceptable for a government to host the Olympic games in an atmosphere characterised by repression and persecution".
The damning assessment comes just over a week before the Olympics kicks off on August 8, in what China hopes will be a grand showcase of its achievements.
Chinese and Olympic officials have said the Beijing games would help expand freedoms in the communist country but the government has instead used it to muzzle critics in the hope of presenting an image of a harmonious society, Amnesty said in its report.
"Unless the authorities make a swift change of direction, the legacy of the Beijing Olympics will not be positive for human rights in China," it said.
|The damning report comes just over a week before the Olympics kicks off [AFP]
"In fact, the crackdown on human rights defenders, journalists and lawyers has intensified because Beijing is hosting the Olympics."
The report documents the use of a "re-education through labour" law to control various types of "offending behaviour" and arbitrary detention for "illegal activities that tarnish the city's image and affect the social order".
It said activists who linked their cause to the games were singled out for action while many others were detained, imprisoned or placed under house arrest.
China has also "increasingly tightened" internet censorship and regulation ahead of the Olympics with journalists at the media centre unable to access certain websites, it said.
"It is very disturbing that Chinese authorities have indulged in such a big crackdown on the activists," Mark Allison, a China researcher for Amnesty, said in Hong Kong.
"These are people who represent many, many more people in China."
The group warned that the pattern of serious human rights violations could "continue or intensify" after the conclusion of the games when China is no longer in the international spotlight.
It urged China to release all prisoners of conscience, stop the arbitrary detention of activists and dissenters, impose a moratorium on the death penalty, allow complete media freedom and account for those killed or detained in Tibet in recent unrest there.