"We have asked that China grant these doctors unhindered access to Liu", Polley said, reiterating U.S. calls for China to grant Liu full parole.
The doctors acknowledged the quality of care he has received and said they agreed with the diagnosis of primary liver cancer.
Meanwhile, the Chinese government has maintained that Liu is receiving the best treatment possible at the First Hospital of China Medical University in the northern city of Shenyang.
"While a degree of risk always exists in the movement of any patient, both physicians believe Mr. Liu can be safely transported with appropriate medical evacuation care and support", oncologist Joseph Herman, of the MD Anderson Cancer Center at the University of Texas, and Markus Buchler, a doctor at Germany's Heidelberg University, said in a joint statement.
Hu Jia, another well-known dissident, welcomed the doctors' statement as very positive, saying it essentially refuted suggestions Mr Liu was too sick to be moved and it paved the way for him to be treated overseas.
"Through the severe punishment meted out to him, Liu has become the foremost symbol of this wide-ranging struggle for human rights in China", the Nobel Committee wrote.
"We have no better method" of treating Mr Liu, it quoted the worldwide experts as saying in response to a question about whether the laureate would receive more effective treatment overseas.
On Saturday, the First Hospital of China Medical University had claimed that travel would prove "unsafe" for Liu, whose condition has deteriorated.
The hospital itself released a brief online statement late Saturday that quoted an unnamed Chinese expert as saying it would be unsafe for Liu to travel overseas.
Shang Baojun, Liu's former lawyer and a close friend, said that during the consultation with the foreign experts, Liu was "clear-headed and communicated smoothly, and could even speak English". Chinese doctors said on Friday that they have stopped using cancer-fighting drugs so as not to overwhelm his severely weakened liver.
Liu, 61, who was jailed by Chinese authorities in 2009 for "subversion" and who was awarded the Nobel Peace Prize in 2010 for "human rights" activities in China, has been diagnosed with liver cancer.
His doctors in China say he is too ill to travel overseas for treatment, and must remain in China.
Hu Jia, a Chinese dissident and family friend, said that Beijing is afraid of letting its most potent opposition symbol go overseas as long as he is able to speak to the media.
"We continue to call on the Chinese authorities to grant Mr. Liu full parole and to release his wife, Liu Xia, from house arrest".
"They don't want to bear too great a responsibility in this respect", he said, referring to the act of allowing Liu to be with his brothers at a critical stage.
The office of the United Nations human rights chief on Friday also expressed concern about Liu's condition and noted that the Chinese government has provided no further information to the U.N. office for more than 24 hours.
China's Foreign Ministry did not immediately respond to a request for comment on whether Mr Liu would be allowed to leave.