US officials and lawmakers took aim at China Wednesday, saying human rights were deteriorating in the communist-run nation as Chinese leaders move to quash even the slightest sign of dissent.

"The overall situation of human rights in China continues to deteriorate," said Michael Posner, assistant secretary of state for human rights, after two days of talks with Chinese officials in Washington.

While he praised China's rapid growth which has lifted "hundreds of millions... out of poverty," Posner also stressed "that political reforms in China have not kept pace with economic advances."

Chinese people needed to be able to voice legitimate grievances and play a "meaningful role in the political development of their own society," he said.

During the talks with the Chinese side, led by Chen Xu, a director general from the Ministry of Foreign Affairs, the US also raised the issue of China's crackdown on the Uighurs, as well as the self-immolations by about 40 Tibetans.

The US delegation also raised concerns about freedom of expression, including Internet freedom, labor rights and legal reforms.

"Lawyers, bloggers, NGO activists, journalists, religious leaders and others are asserting universal rights and calling for peaceful reform in China," Posner told reporters.

"We strongly believe as change occurs within a society these discussions... are ultimately about Chinese aspirations and how the Chinese themselves are navigating their own future."

US officials voiced concern about the lack of access to legal counsel for detained activists, and again called for the release of lawyers and democracy activists languishing in jail, including Nobel peace laureate Liu Xiaobo.

They also raised the cases of prominent Chinese rights lawyer Gao Zhisheng, who has been held virtually incommunicado since 2009, and wheelchair-bound Ni Yulan, who was jailed after working with her husband to protect alleged victims of government-backed land grabs.

The US delegation comprised representatives from across the administration, including from the justice department, USAID, trade representatives and national security staff.

Posner dismissed suggestions that the regular US-China human rights dialogue was of little use since conditions were not improving on the ground.

"I think over time we're responding to a very heartfelt desire by people living in China... that their cases, their issues not be forgotten. We're amplifying their voices, in effect," he told journalists.

US lawmakers also took Beijing to task for its "deplorable" human rights record at a hearing in Congress, while advocates called on President Barack Obama to personally engage with the Chinese on rights cases.

Four human rights defenders, including Chinese Uighur rights defender Rebiya Kadeer, testified to the House Foreign Affairs Committee about the deteriorating conditions in China and Tibet.

"Chinese authorities remain hyper-vigilant about tamping down anything that smacks of political or social dissent, including criticism of the government and exposure of official wrongdoing," Howard Berman, the committee's ranking Democrat, told the hearing.

Dissident Chen Guangcheng, who arrived in the United States in mid-May, had been due to testify, but later declined apparently out of fear of reprisal against relatives back in China.

The 40-year-old activist, jailed for four years for exposing abuses under China's one-child policy, escaped from house arrest in April just as Secretary of State Hillary Clinton was visiting Beijing, sparking a major diplomatic incident.

While some of the advocates said such forums as the US-China dialogue on human rights were vital to keep pressure up on Beijing, they all called for the White House to do more.

"At the highest levels it has not been a priority," Jared Genser, founder of US-based non-profit group Freedom Now, told lawmakers.

"President Obama and Secretary Clinton must personally engage on Chinese human rights cases and make full use of the bully pulpit, something they have only done to date on rare occasions," he added.

"China's backsliding on rights should have long since merited a change in tactics and a more proactive and public approach."