Chinese dissident Chen Guangcheng has accused Beijing of a pattern of abuse against his family as he again took his case to US legislators.

Chen, a blind self-taught lawyer who last month dramatically escaped house arrest for the safety of the US embassy, telephoned a hearing of the US Congress for the second time this month from a hospital bed in Beijing.

Unlike in the previous hearing, Chen did not voice concern over his own conditions. But he charged that local authorities in the eastern province of Shandong were seeking revenge by filing a murder charge against his nephew.

"These are trumped-up charges. Those people in Yinan county have already been on the opposite side of the rule of law in China," said Chen said as one of his most prominent supporters, Chinese dissident Bob Fu, translated for members of the House Foreign Affairs Committee.

Chen said government-backed thugs broke into his nephew Chen Kegui's house and beat him up for three hours with stakes until his face was bloody, with police detaining him when he fought back. Despite the murder charge, no one was reported dead.

Chen said "this is a pattern," accusing authorities of launching the same sort of campaign against his nephew as they did to him.

Chen served four years in jail on charges that included disruption of traffic.

Chen had riled authorities by exposing forced abortions and sterilisations by officials meeting quotas under China's one-child only policy. Chen has said he was subjected to brutal beatings under house arrest because he continued to speak out after his release from jail in 2010.

Visa ready for family

On Capitol Hill, Chen spoke to House Representative Chris Smith, a longtime campaigner against China's one-child policy.

Chen broke several bones as he climbed walls to escape house arrest, and then undertook a risky journey by car to Beijing, where he later sought refuge at the US embassy.

US officials escorted him to a hospital on May 2, saying that China had made assurances for his safety.

But Chen telephoned a congressional hearing a day later, saying he feared for the safety of himself and his family. He said he wanted to leave for the US and appealed for a meeting with Secretary of State Hillary Clinton, who was visiting Beijing.

American officials said that China had agreed to allow Chen to travel soon to the US to study.

State Department spokeswoman Victoria Nuland said on Tuesday that US visas were ready for Chen, his wife and their two children.

"We are ready when he and his government are ready," Nuland told reporters.