Deceased Chinese Nobel Peace Prize-winning dissident Liu Xiaobo's ashes were scattered at sea on Saturday, Liu's brother said, in a move described by a family friend as an effort to erase any memory of him.

Liu, 61, died of multiple organ failure on Thursday in a hospital in the northeastern city of Shenyang, where he was being treated for late-stage liver cancer, having been given medical parole but not freed.

He had been jailed for 11 years in 2009 for "inciting subversion of state power" after helping to write a petition known as "Charter 08" calling for sweeping political reforms.

His widow, Liu Xia, has been under effective house arrest since her husband won the Nobel Peace Prize in 2010, but had been allowed to visit him in prison about once a month. She has never been formally charged with any crime.

Speaking at a government-arranged news conference, Liu Xiaobo's eldest brother Liu Xiaoguang offered thanks several times to the Communist Party for its thoughtful care considering the dissident's "special situation".

"Why has Liu Xia not come here? Her health is very weak at the moment," Liu Xiaoguang said, sitting in-between an English-language interpreter and a Shenyang government official. "So she can't come here. It's very regretful."

After speaking for about 20 minutes, Liu was escorted out by two unidentified women, an unlit cigarette in his mouth, and did not answer questions from journalists who surrounded him.

The government then showed reporters images of the ashes being scattered from a boat.

City government information official Zhang Qingyang said Liu Xia and Liu Xiaoguang had decided upon the scattering of ashes at sea.

But close friend and fellow dissident Hu Jia said the motivation behind the sea burial was so that there was "nothing to remember him by on Chinese soil" and so that supporters could not create a shrine to pay tribute to him.

"We know that Liu Xiaobo's home is Beijing, his spiritual home is here, his love was also found here," he said.

Hu said it was well-known among Liu's friends that his elder brother did not agree with his political views and that it was a cynical move for him to be presented to the media as representing Liu Xia and the family.

"The extent to what the authorities are capable of always exceeds our imagination, they always have something worse than imagined planned," Hu said of the news conference.

Nicholas Bequelin, Amnesty International's East Asia Regional Director, tweeted that the news conference was "one of the most crude, cruel and callous political show(s) I have ever witnessed".

Government official Zhang, speaking earlier, said Liu's widow was "currently free", adding that as a Chinese citizen, her rights would be protected under the law.

"But she just lost her spouse. She is extremely sad. In the period after dealing with the death of Liu Xiaobo, she won't take anymore outside disturbances. This is the wish of the family members. It's natural."

Zhang did not say where Liu Xia currently was.

A government statement said Mozart's Requiem was played during the funeral, a work of music Mozart left unfinished on his death bed.

Liu family lawyer Mo Shaoping told Reuters he did not know whether the cremation was in accordance with family wishes, however, as they had been unreachable.

"They are likely still to be under the watch and control of authorities," Mo said. "They can't be contacted."

In funeral photographs handed out by the government, Liu Xia and other family members stand around the coffin containing Liu's body, surrounded by white flowers that signify mourning in China.

During the past couple of weeks, Liu Xia had been at the hospital as her husband's health deteriorated.

Rights groups and Western governments have mourned Liu Xiaobo's death and urged authorities to grant freedom of movement to his wife and the rest of his family.

China has repeatedly attacked foreign governments for their concern about Liu and calls to allow Liu Xia to leave the country if she wishes, and foreign reporters in Shenyang have been closely monitored by plainclothes security.

Efforts are being made to secure permission from Chinese authorities for Liu Xia and her brother Liu Hui to leave, a Western diplomat said on Friday.

The last Nobel Peace Prize winner to live out his dying days under state surveillance was Carl von Ossietzky, a pacifist who died in Berlin in Nazi Germany in 1938.