As Winter Olympians vie for gold in Beijing, global attention has turned to events in the extensive Olympic "bubble" -- a zone sealing off visiting athletes, media and participants from the rest of the host city to prevent the spread of Covid-19.

But in a different part of Beijing, prominent human rights activist Hu Jia is again living in another kind of bubble: what he says is a house arrest imposed by authorities who want him out of public view during the Games.

"They said Winter Olympics is a very important political event and no 'disharmonious voice' will be allowed -- like any criticism of the Winter Olympics, or any talk related to human rights," said Hu, who spoke to CNN during what he describes as a weeks-long restriction to his home.

"In China, people like me are called 'domestic hostile forces'... that's why they have to cut me off from the outside world," said Hu, who gained international prominence as a champion of human rights in the early 2000s and was a friend to late Nobel Peace Prize winner and dissident Liu Xiaobo.

Hu says he has been restricted to his residence, with the exception of trips to care for his ailing mother, since January 15. It's an escalation of the round-the-clock state surveillance Hu says he has been under for nearly two decades. It's also treatment he has become used to during sensitive political events in China. Hu said he was originally told to leave Beijing altogether and relocate to Guangdong during the Olympic period but an outbreak of Covid-19 prevented him from going.

Human rights activist Hu Jia in Beijing in 2013.
But Hu is far from the only dissident facing restrictions in the months leading up the Winter Games.
William Nee, research and advocacy coordinator at Chinese Human Rights Defenders, a non-profit network supporting rights advocates in China, said before the Winter Games there had been an uptick in reports of state security wanting to know people's whereabouts, house arrests and the detention of high profile activists and lawyers.
"The Olympics has given China an opportunity to showcase its international clout and it doesn't want pesky activists disrupting that and talking about its human rights abuses," he said, adding that many prominent rights defenders are "surveilled by state security all the time" or subject to other measures of control.
Rights experts say that crackdowns on activists and speech -- which can range from closing social media accounts to house arrests, detentions or enforced disappearances -- are typical in the lead up to sensitive events in China, where the Communist Party keeps a tight lid on dissent.
"The point is to prevent any contact between the activists and, essentially, the outside world, which, during these events, tends to pay more attention to what's happening in China," said Maya Wang, a senior China researcher at the New York-based non-profit Human Rights Watch.
But controls on dissent have been getting tighter year-round, blurring the line between normal and sensitive periods, according to observers.
"The human rights environment in China has deteriorated pretty significantly in the last decade," Wang said.

Guards secure barriers after a bus arrives at a hotel that is part of the Olympics closed loop bubble.

A shadow over the Games
Concerns over China's human rights record have already cast a shadow over Beijing's Olympic Games, including a US-led diplomatic boycott over what Washington calls serious human rights abuses against Uyghur and other Muslim minorities in the country's far-western region of Xinjiang.
China has denied these charges and pushed back on international concerns about its human rights record, calling these "political posturing and manipulation" in the lead up to the Games.
Following a faxed request for comment on allegations that Hu Jia has been forcibly confined to his home during the Winter Olympics, and that other human rights activists have also been detained or monitored, China's Ministry of Public Security referred CNN to Beijing authorities. Multiple calls to the Beijing municipal government went unanswered.
Hu, who rose to prominence for his activism related to HIV/AIDS in rural China, says the house arrest began after he posted on Twitter -- a platform banned in China -- describing a ramp-up of restrictions and controls on activists in the lead up to the Beijing Games,. He also noted the circumstances of jailed or missing dissidents while using a Winter Olympics hashtag in Chinese.
Since then, security agents have visited him multiple times, Hu says, including once this week to instruct him not to discuss Olympic skier Eileen Gu. That was after Hu commented via Twitter on an article about the US-born athlete who is representing China at the Beijing Games.

Hu says he expects this period of house arrest could last through the country's annual legislative gathering next month. He says he'll spend the time reading.
"It's so much better than my friends who are suffering in jail and prison. We are like (the difference between) heaven and hell, so I have nothing to complain about," Hu said in a recorded video dairy, where he is documenting this period of house arrest for CNN.
"There is some level of stress for sure, my mental health, and so on. After all, you always want to be able to walk out of your home freely and stand under the bright sky," he said in another entry.
But Hu is no stranger to harsher forms of confinement.
Just months before Beijing hosted its last Olympics in 2008, Hu was handed a three-and-a-half year prison term for "incitement to subvert state power" -- a sentence that activists at the time linked to his work calling international attention to human rights abuses in China ahead of the Games.
This time, Hu watched the Olympic opening ceremony from his elderly parents' home in Beijing -- the one place he says the security agents will allow him to visit and a privilege he says they have threatened to deny if he acts out. He also says if things escalate he could be imprisoned again. But nonetheless, Hu has a message.
"This might be the only Olympics in history that has drawn so much attention to its host country's human rights issues. This is a really good opportunity to explore and discover China's human rights issues, including Uyghurs, Tibetans, Hong Kongers, Taiwanese... and also citizens, human rights activists, and dissidents like us who are in mainland China now," said Hu.
"I hope the world will see this clearly and pay more attention to human rights issues...not just during the Winter Olympics...but also keep watching democracy, human rights, and the future of China," he said.