The dissident who was at the center of a standoff between China and the United States on Wednesday accused Beijing of failing to live up to its promises as US lawmakers rallied behind him.

Chen Guangcheng, a blind activist who was jailed after exposing abuses in China's one-child policy, has lived in New York since May 20 after a dramatic escape from house arrest to the US embassy in Beijing.

Visiting Congress in his highest-level contact yet with the US government, Chen voiced concern for his nephew who was arrested soon after the dissident fled China's eastern province of Shandong for Beijing.

"The Chinese central government explicitly promised me that it would thoroughly investigate the extended oppression and abuse that I endured in Shandong province," Chen, flanked by lawmakers, told reporters in the Capitol.

"The government further promised to provide for the security of my family. However, it has been more than three months and I have not received any news on the progress of this investigation or even whether it has commenced," he said.

Chen complained that no Chinese official has contacted him since he arrived in the United States. China had said that it was allowing Chen to go abroad with his family to study, but some experts presumed that China's main motivation was to get rid of Chen and doubted he would be able to return.

Authorities have charged his nephew, Chen Kegui, with attempted murder. The dissident said that his nephew was defending himself with a kitchen knife after thugs liked to the local government broke into his home.

Speaking before a meeting with US lawmakers, Chen said that the human rights situation was deteriorating in China but that change was inevitable as citizens make their voices heard.

"I sincerely hope that the United States and all other nations that embrace the fundamental values of constitutionalism, democracy, freedom and the rule of law will support and assist with a smooth transition in China," Chen said.

Chen enjoyed a rare bipartisan welcome in the polarized Congress, meeting jointly with House Speaker John Boehner, the top elected Republican, and Representative Nancy Pelosi, the House leader of President Barack Obama's Democratic Party.

Boehner said that the United States should speak out over human rights abuses in China, including its "reprehensible" one-child policy.

"When it comes to guaranteeing the freedom and dignity of all of her citizens, the Chinese government has a responsibility to do better and the United States government has a responsibility to hold them to account," Boehner said.

Chen later met separately with Senator John Kerry, the Democratic chairman of the Senate Foreign Relations Committee, who called the dissident's story an "inspiration" and said the pair spoke about Chen's nephew.

"Chen Kegui must be treated fairly and humanely, and granted access to whatever defense counsel he chooses," Kerry said in a statement.

Chen Guangcheng fled to the US embassy days before Secretary of State Hillary Clinton paid a previously scheduled visit to Beijing.

Clinton and her aides brokered the deal for Chen's departure and she spoke to him by telephone but she did not meet him, as part of an apparent understanding with China to keep US statements at a low level.

A State Department official said that US diplomats have maintained contact with Chen and met with him privately as recently as last week, but did not plan to see him during his trip to Washington.

Chen was sentenced to more than four years in prison in 2006 after accusing authorities in Shandong province's Linyi county of forcing up to 7,000 women to undergo late-term abortions or sterilizations.

He was released in September 2010 but said that he was afterwards put under a harsh house arrest, with thugs beating him severely in an unsuccessful attempt to silence him.