"The No. 1 Affiliated Hospital of China Medical University (in Shenyang) has formed a medical team comprised of eight nationally renowned oncologists and drawn up a treatment plan," it said. "Liu is currently being treated in accordance with the plan."

Calls for release

The Norwegian Nobel Committee said while it was "delighted" Liu was out of prison, "Chinese authorities carry a heavy responsibility if Liu, because of his imprisonment, has been denied necessary medical treatment."

"The Committee hopes that he will now be released without conditions and offered the best possible treatment for his illness, whether it be in China or abroad," it said in a statement.

In a statement, Wu'er Kaixi and Wang Dan -- two of the leaders of the 1989 Tiananmen protests -- said they were "shocked and devastated" by the news.

"We believe that Liu Xiaobo's physical and mental suffering in China's prison system is the fundamental cause of the deterioration of his health," they said.

"We strongly urge the Chinese government to immediately give Liu Xiaobo comprehensive medical care, to allow an outside medical team to visit and help him, and we also firmly demand immediate restore of Liu Xiaobo's normal contact with the outside world."

Nobel peace prize

A prolific writer and longtime activist, Liu had been in and out of jail since the bloody crackdown on pro-democracy protesters in Beijing's Tiananmen Square in 1989.

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.

Despite China's refusal to let Liu or a representative travel to accept the award, the Nobel ceremony organizers placed his citation and medal on an empty chair in a poignant event held in Oslo in December 2010.