BEIJING (Reuters) - Premier Li Keqiang said on Thursday China’s constitution protects human rights after he was asked about Liu Xia, the widow of Nobel Peace Prize-winner Liu Xiaobo, with concern growing that Beijing will not allow her to leave the country.

China's Premier Li Keqiang speaks at a joint news conference with German Chancellor Angela Merkel (not pictured) at the Great Hall of the People in Beijing, China, May 24, 2018. REUTERS/Jason Lee/Pool

Liu Xia, an artist and poet who suffers from depression, has been under effective house arrest since her husband was awarded the prize in 2010. She has never been charged with any crime.

Liu Xiaobo died of liver cancer in July while in Chinese custody, having been jailed in 2009 for inciting subversion.

Li answered a question about Liu Xia’s freedom by saying China’s constitution states that it respects and protects human rights. He said at a joint briefing with German Chancellor Angela Merkel in Beijing he hoped China and Germany could talk about individual human rights cases on an equal basis.

“China will respect the actions taken in accordance with the law by judicial and law enforcement bodies, but at the same time we must respect humanitarianism and follow humanitarian principles,” Li said.

“On relevant individual cases, we hope to have dialogue on the basis of mutual respect and equality. We will explain our situation,” Li said, without elaborating or mentioning Liu Xia by name.

Merkel had brought up human rights issues with him and China was willing to hold talks on the subject with Germany by the end of this year, he said.

China has repeatedly said Liu Xia is free and is accorded all rights guaranteed to her by Chinese law.

However, Beijing-based Western diplomats say she has been closely monitored by Chinese authorities since her husband’s death and has only been able to meet and speak to friends and family in pre-arranged phone calls and visits.

Repeated delays by Beijing in recent months over discussions that would allow Liu Xia to leave China have raised concern that she will be unable to fulfill her wish to live overseas, a Western diplomat involved in the case told Reuters.

Dozens of writers, poets and artists from around the world called last week for China to release Liu Xia after a friend who lives in Germany released details of a phone conversation where Liu Xia said she was prepared to die in China.

Western diplomats in Beijing took the rare step two weeks ago of attempting to visit Liu Xia in her home but were turned away by security personnel, an official of one of the embassies involved told Reuters. The official declined to be identified.