Beijing (CNN) -- Talks between China and the United States about human rights issues, including missing Chinese activists, ended Thursday with little progress and many unanswered questions, a U.S. diplomat said.
"It was a tough set of discussions," said Michael Posner, the U.S. assistant secretary of state for democracy, human rights and labor. "Our disagreements are profound."
The Beijing meetings came at a particularly frosty time in U.S-China relations, with diplomatic sparring between the two countries.
"In recent months, we've seen a serious backsliding in human rights," Posner said.
U.S. Secretary of State Hillary Clinton recently said she was "deeply concerned" about the arrests of dozens of activists in China.
Both sides engaged "frankly and candidly" in the meetings, which focused largely on the status of dozens of recently detained activists and a series of disappearances.
"The dialogue was respectful in tone and based on the facts," Posner said. "And the facts are not good."
Beijing has been silent on a long string of detentions and arrests of activists and lawyers in the aftermath of anonymous calls for a Middle East-style "Jasmine" revolution.
The Chinese government has responded with a wider crackdown on musicians, artists and religious groups in recent weeks.
"We have been very concerned that dozens people have been arrested and disappeared with no regard to legal measures," Posner said at a Beijing news conference at the end of the talks Thursday.
Posner said the U.S. delegation inquired about several missing Chinese activists, including lawyers Teng Biao, Chen Guangcheng and Gao Zhisheng. Police took Gao in April 2010, and his family hasn't seen him since.
Posner also filed a formal request to meet with Liu Xia, the wife of Nobel Peace Prize laureate Liu Xiaobo. She's been under house arrest without any formal charges since her husband won the prize last fall. A meeting has not been scheduled.
Posner called Liu Xiaobo's 11-year prison sentence "unacceptable and a violation of the right to basic free speech."
The status of artist and critic Ai Weiwei, who has been detained without being charged since April 3, also remains a mystery, Posner said.
"We certainly did not get answers that satisfied," he told journalists. "There was no comfort in the response or rather lack of response."
Chinese officials had little to say about the human rights dialogue.
"We oppose any country interfering in China's internal affairs under the pretext of human rights issues," Foreign Ministry spokesman Hong Lei said at a news briefing Thursday.
The editorial pages of Chinese state-run media called the U.S. diplomats "aggressive" and "offensive in dialogue." The same article, appearing in the Global Times, asserted most Chinese people "are disgusted with Western pressure on human rights."
U.S. diplomats disagreed.
"Human rights are not about us, but about how Chinese citizens determine their own future," Posner said. "We are reinforcing what Chinese people themselves are asking."
Posner pointed to a tightening political climate as the root cause of China's actions.
"There is no question the atmosphere is different," Posner said. "Both sides recognized that."
As for how it will affect the ever important U.S.-China relationship, Posner was cautious.
"Protecting human rights is one essential feature of what we do as the United States," Posner said. "When you have a deterioration as it has been here, it makes the relationship more difficult."
The tone of this week's discussion are a far cry from Chinese leader Hu Jintao's visit to Washington in January, where he publicly acknowledged "a lot still needs to be done in China in terms of human rights."
This session of the U.S.-China Human Rights dialogue is the 16th meeting of its kind.
Posner told reporters that human rights topics would also be discussed in next month's U.S.-China Strategic and Economic Dialogue to be held in Washington.
Posner said a dialogue between Chinese and American legal experts, which was first proposed during Hu and Obama's January meetings, will take place in June.