Hours after the foreign doctors announced their opinion, Jared Genser, a Washington-based lawyer who represents Liu internationally, said that any decision by Chinese authorities to still keep Liu would amount to "intentionally hastening his death" and "refusing to honor the wishes of a dying man to receive the treatment he desires".
Liu was granted medical parole last month after he was diagnosed with late-stage liver cancer in May.
The doctors, who were invited by the hospital at Liu's family's request, found that Liu was had excess abdominal fluid and was in serious condition, the hospital said on its website.
Joseph Herman from the University of Texas' cancer centre and Markus Büchler of the University of Heidelberg surgery department, released a joint statement saying a medical evacuation would have to happen "as quickly as possible".
It was impossible to independently verify the hospital's description of their views.
Furthermore, the experts are unlikely to be able to speak about Liu's condition, Poon said.
Shang Baojun, a former lawyer for Liu who remains close to the family, told The Associated Press on Saturday that Liu was coherent enough during the visit with the foreign doctors to say that he wanted to go overseas for treatment, preferably to Germany, although the US would also be fine. "We sincerely hope this request will be approved".
The doctors' visit comes as Chinese President Xi Jinping is in Hamburg, Germany, for a G20 summit ending Saturday. Chinese doctors said Friday that they have stopped using cancer-fighting drugs so as not to overwhelm his severely weakened liver.
"We will continue to provide nutritional support, pain relief and other forms of supportive care to improve the patient's quality of life as much as possible", the hospital's statement said.
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I know she has only just come back, but I expect her to be playing really well because I know she will have put in the hours and the work.
A friend of Liu's, who asked to remain anonymous due to the case's sensitivity, told AFP that both his younger and older brothers are set to visit him in the hospital for the first time this weekend.
His wife, Liu Xia (劉霞), has been under house arrest since 2010.
"I think the authorities are in crisis mode".
But the hospital said the experts concurred that Mr Liu has been afforded top medical care from renowned doctors.
Critically ill: Liu Xiaobo.
Hu Jia, a prominent Chinese activist, said the constant updates of Liu's health showed the authorities "are feeling the pressure".
Human rights advocates have criticized the government for not treating Mr. Liu's illness earlier and have called on Chinese officials to allow him to receive treatment overseas.
American officials on Sunday reiterated calls to allow Mr. Liu, who was awarded the Nobel Peace Prize in 2010 for his human rights advocacy, to seek care overseas.
The United Nations human rights office demanded on Friday that the UN be given access to Liu.
It said a traditional Chinese medicine anti- tumour treatment was also suspended while low-molecular heparin had been added to treat venous thrombosis developing in Liu's left leg.