The winter games are scheduled to begin on Feb 4 next year, just six months after the delayed summer Tokyo Olympics, but preparations have been overshadowed by the coronavirus pandemic.
China is also facing global scrutiny over a range of issues, notably the mass internment of Uighur Muslims in western Xinjiang region, and its clampdown in Hong Kong.
Around 180 campaign groups signed the open letter, which called on world leaders to boycott the Beijing Winter Games “to ensure they are not used to embolden the Chinese government’s appalling rights abuses and crackdowns on dissent”.
The coalition, which includes the World Uyghur Congress and International Tibet Network, said that since Beijing was awarded the Games in 2015, “President Xi Jinping has unleashed an unrelenting crackdown on basic freedom and human rights”.
In a statement to AFP, the International Olympic Committee (IOC) said that concerns raised by campaign groups, including over rights, “were and are raised with the government and local authorities”.
“We received assurances that the principles of the Olympic Charter will be respected in the context of the Games,” the IOC said.
“We will continue to discuss Games-related issues with the organisers.”
China has been under growing pressure - particularly over the fate of its Uighur minority.
Rights groups believe that at least one million Uighurs and other Turkic-speaking Muslim minorities are incarcerated in camps in Xinjiang.
After initially denying the camps existed, the Chinese government abruptly acknowledged them, saying they were vocational training centres aimed at reducing the allure of Islamic extremism.