It was a telling sign of the waning momentum of China 's human rights movement: the name of China's most famous political prisoner was not even officially brought up as Chinese President Xi Jinping and German Chancellor Angela Merkel instead bonded over pandas and soccer.

As Nobel Peace Prize laureate Liu Xiaobo struggles on his sick bed in a heavily guarded Chinese hospital, leaders of G20 nations gathered in Germany made no official mention of the activist.

Given the treatment of Liu and the government's massive crackdown on lawyers and activists since July 2015, observers say the disappearing pressure over China's rights record could in turn embolden Beijing to turn the screws further on dissident voices.

"The effect of foreign pressure on the [Chinese] government is diminishing," said Link, a comparative literature and foreign languages professor at the University of California at Riverside who co-translated the Tiananmen Papers, which detailed the Chinese government's response to the 1989 democracy protests. He also translated into English "Charter 08", the document that Liu co-authored calling for political reform in China.

Former political prisoner Wei Jingsheng, who spent about 18 years in jail, was released at the request of former US president Bill Clinton . Wei was deported by Beijing in 1997 after being granted medical parole, and headed to the US.

Late Chinese astrophysicist Fang Lizhi, who was among the "black hands" blamed for instigating the 1989 Tiananmen Square protest, was welcomed into the Beijing embassy on June 5 that year as a guest of former US president George Bush with the help of veteran sinologist Perry Link. Fang and his wife hid in the embassy for 13 months before going on to live as exiles in the US. They also could be thankful for the negotiations of diplomat Henry Kissinger and Brent Scowcroft, who was then the US national security adviser.

This is in stark contrast to the days when international pressure could make a difference in the fate of individuals fighting for rights in China – when Beijing was still sensitive enough to listen.

Rather than upset the leader of the world's second-largest economy and a major global ally, officials of foreign nations would rather keep their lips buttoned in public and focus on trade and bilateral ties.

Maya Wang, a senior researcher with Human Rights Watch's Asia division, warned that the Chinese government would be "rewarded and encouraged [to continue] its impunity in mistreating political activists".

"If G20 nations fail to publicly press the Chinese government to free Liu, they would lose credibility in pressing for human rights everywhere, not just in China," Wang said.

China has gathered economic strength and political influence as its authoritarian regime expanded in the years following the 2007-08 global economic crisis.

Steve Tsang, director of the SOAS China Institute in London, said: "The size and importance of the Chinese economy, with all that entails, meant others are now much more careful in raising human rights issues with Beijing."

Recent examples of foreign governments putting economic interests ahead of lobbying for rights in China indeed suggest the nation is rich enough to mute critics. Cases in point are the financially embattled Greek government's vetoing of a European Union statement condemning China's rights record at a UN meeting last month and Norwegian Prime Minister Erna Solberg's refusal last week to comment on calls for Liu's release. Bilateral ties between Norway and China were only normalised in December following a six-year freeze that began when Liu, by then behind bars, was awarded the 2010 Nobel Peace Prize in absentia.

Robert Daly of the Kissinger Institute on China and the United States at the Washington-based Woodrow Wilson Centre, said Beijing was aware its authoritarianism prevented it from gaining the international respect it sought; but it needed to weigh global approval against domestic stability, especially when "[global] concerns over human rights" could be bought off.

"For now, China can be confident that the West will not launch an effective challenge to Beijing's crackdown on free expression," Daly said.

He added that Beijing had also grown "more self-certain" by providing "investment, aid and other international public goods which are winning it international influence, if not admiration".

China demonstrated its unwillingness to put up with any more criticism of its rights record in June last year, when Foreign Minister Wang Yi vented his anger at a Canadian journalist who raised the issue at a joint press conference with the Canadian foreign minister in Ottawa.

"Other people don't know better than the Chinese people about the human rights condition in China and it is the Chinese people who are in the best situation, in the best position, to have a say about China's human rights situation," Wang said, going on to label the journalist's questions "groundless and unwarranted accusations".

Tsang said Beijing "does not feel that foreign powers have any right to put pressure on what it sees as domestic affairs".

"As far as the [Communist Party] is concerned, China's human rights conditions are excellent, and no changes are required, though there would always be scope for the party to take an even stronger leadership role," Tsang said. "If they see no problem, they see no scope for improvement, only scope for the party to tighten control."

Beijing previously appeared less inured to international pressure, which was credited with playing a role in improving the treatment of individual human rights defenders.

In February 2007, Gao Yaojie, a retired gynaecologist best known for her Aids-prevention work during an HIV epidemic in Henan province, was placed under house arrest. However, the local authorities soon bowed to international pressure and allowed her to travel to the US, where she now lives.

In previous decades, Western countries collectively pressured China to improve its rights record, but that was no longer the case, Daly said.

"Since the second world war, the United States and many other free nations have believed that promoting representative governance, open markets and human rights worldwide served their national interests. That commitment seems to be fading, but whether this is a long-term trend or a temporary fashion is uncertain," Daly said.

"Is there still a collective West capable of expressing values or acting in concert in the absence of American leadership? The presidency of Donald Trump and growing nationalism in other nations have called the idea of the West into question. I think the historical validity of "the West" runs deep and that it is profoundly in the West's interest that liberalism remains a global force, but that can't happen in the absence of leadership."

Blind civil rights activist Chen Guangcheng, who set off a diplomatic crisis in April 2012 when he escaped house arrest after surviving extensive torture and fled to the US embassy in Beijing, said he had the international community to thank for being allowed to leave China with his family a month later.

He told the South China Morning Post recently that Liu's situation could be compared to that of Otto Warmbier, an American student who was sentenced to 15 years of hard labour for stealing a propaganda banner during a visit to North Korea last year and who died six days after being released on medical parole last month.

"When democratic countries led by the United States are tolerating or compromising in exchange for cooperation with China, this hurts the interests of civilians living under the authoritarian regime and their own international reputation," Chen said. "It's not that the US is running out of means to pressure China in freeing Liu Xiaobo, but rather if they would play the card on moral grounds serving the nation's founding values."

Although Chen managed to flee China under US' lobbying, he still harbours mixed feelings over his rescue in 2012. Chen said he was first warmly received by the deputy ambassador, who "personally took me into the embassy".

"But I soon felt a change of attitude on the 27th [of April], when [former US president Barack] Obama had a change of heart and decided to "not affect the Sino-US bilateral relationship based on human rights", Chen said.

"No one at that point would stand up [for] human rights and they wanted to get me out of the embassy," he said.

Chinese and US governments negotiated his fate. When he left the embassy six days later, US officials said Chen would have preferred to stay in China but pleaded for help to leave.

Although he was able to depart for the US two weeks after the ordeal, Chen, who now lives in the US, said he felt abandoned after Obama put China and US ties before him.

Gary Locke, who was the US ambassador in Beijing when Chen was seeking refuge at the embassy, urged the US to remain vigilant and outspoken about human rights.

"Concern for human rights is in the DNA of America ... it is unfortunate that [US] President [Donald] Trump is not as forceful on the issue as past presidents, both Democratic and Republican," Locke told the Post.

He called on China to immediately release Liu on humanitarian grounds and allow him to seek medical care overseas with his family.

"That would be the kind and decent thing to do, but that would also enhance China's image in the world," Locke said.

Apart from economic interests, foreign nations rely on China for help in dealing with many other issues, including climate change, the fight against terrorism and resolving the nuclear crisis in North Korea, veteran activist Hu Jia said.

"Hence, they are forced to make compromises to soften their stances over human rights," Hu said.

Calls on China to free rights activists are often met with strong opposition from the government, which has sternly warned Western countries not to "meddle in Chinese domestic affairs".

"Xi Jinping will not want to be seen as caving in to foreign pressure in the run-up to the 19th party congress," Daly said. "He won't want to appear weak."

The exiling of Chinese dissidents in past decades had done nothing to strengthen the rule of law in China or improve civil liberties, he said.

However, Link said "China is much bigger than the Communist Party of China and the motive in China to improve human rights will live longer than the CCP does".

"[Liu Xiaobo's plight] will highlight [China's human rights] issue, at least for a time. But long-term improvement can come only from inside China, including Hong Kong," he said, adding: "There are still plenty of smart and good people in China".

That sentiment was also shared by veteran activist Hu, who said he believed that momentum to improve human rights lay within China.

"Even the darkest darkness cannot stop the light within humanity to shine through," he said. "Humanity even prevailed over the worst, even during the madness of the Cultural Revolution.

"China's real social reform will come from the people themselves," Hu said. "Civil awareness is consolidating as the economy grows and private rights protection is enhancing."