In late June the dissident was transferred from prison to a hospital because of advanced liver cancer.
Mr Liu has an abdominal infection, organ dysfunction and he went into septic shock, the hospital said in a statement on its website.
U.S. and German cancer experts visited Liu last weekend and determined that he was strong enough to be medically evacuated, but the hospital has issued pessimistic medical updates since then. He was sentenced to 11 years' jail on subversion charges but was awarded the Nobel Peace Prize in 2010.
The family of China's cancer-stricken Nobel laureate Liu Xiaobo declined to let doctors put him on artificial ventilation, his hospital said, raising the grim prospect that he could die in custody.
The back-to-back pessimistic reports from the hospital came after foreign doctors who visited Liu over the weekend concluded that it was safe to transport him to another country, contradicting their Chinese counterparts.
China has in the past released high-profile dissidents on medical grounds and immediately exiled them to the United States, notably veteran democracy campaigner Wei Jingsheng in 1997 and a leader of the 1989 student pro-democracy protests, Wang Dan, in 1998.
"So long as Liu is still breathing and conscious, we should keep calling for him to be released and go overseas with Liu Xia, even if it is the last thing he does", Hu said.
His most recent conviction, on Christmas Day 2009, stemmed from his co-authorship of Charter 08, a manifesto calling for political reform and human rights in China.
Liu, China's most famous political prisoner, is now battling liver cancer at the First Hospital of China Medical University in the northeastern Chinese city of Shenyang.
"The economy is strong, the military is rising does China still care about global political opinion?" said Zhang Lifan, a liberal political commentator in Beijing.
However, a family member said Liu's condition had improved on Wednesday morning.
News searches for Liu's name on Baidu, China's largest internet search engine, have turned up no hits since February.
A group of volunteers comprising Liu's friends and activists from China, Hong Kong and Taiwan began a petition on Change.org, to call for the release of the renowned dissident which has reached over 34,000 signatures in just 10 days, according to a statement released on Wednesday.
A video clip leaked on Monday appeared to show one of the foreign experts who visited Liu, Markus W. Buechler of Heidelberg University, addressing Liu's wife, Liu Xia, to tell her that Chinese doctors were doing their utmost to help Liu and were "very committed to his treatment".More news: Major technical glitch hits National Stock Exchange; cash, F&O trade affected
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