US lawmakers and activists called for persistent pressure Tuesday until China allows activist Chen Guangcheng to travel overseas, after a showdown between the two nations over his treatment.

US officials said May 4 that China would allow the blind self-taught lawyer to leave soon to study in the United States, after he dramatically fled house arrest and took refuge in the US embassy.

Chen, who angered authorities by exposing forced abortions and sterilization under China's one-child policy, remains in a Beijing hospital for treatment of injuries, with Chinese officials publicly quiet on his case.

Bob Fu, a Chinese dissident who has been instrumental in raising Chen's case, voiced hope that Chen and his family would be able to come to the United States "very soon."

"I hope that Congress will do more in monitoring and urging the administration to ensure the civil rights of Chen Guangcheng and his family members are protected by the law," Fu, founder of the Texas-based Christian group ChinaAid, told a congressional hearing.

At another hearing on May 3, Fu arranged for Chen to call lawmakers and appeal for help. Chen said he feared for his relatives' lives and wanted a meeting with Secretary of State Hillary Clinton, who was visiting Beijing.

Chen had left the US embassy a day earlier after US officials said that China would ensure the safety of the dissident, who has recounted severe beatings since he was freed from jail in 2010 and put under house arrest.

State Department officials, faced with strong criticism by Congress and Republican presidential contender Mitt Romney, said that Chen had never requested asylum but changed his mind after leaving US protection.

At the latest hearing, Fu praised the "great active efforts" by diplomats, including Ambassador to China Gary Locke and Assistant Secretary of State Kurt Campbell, but said some issues initially "were not handled appropriately."

Representative Chris Smith, a longtime campaigner against forced abortion who chaired the two hearings, voiced concern about harassment of Chen's supporters, including Jiang Tianyong, a human rights lawyer who said he was beaten so badly he lost hearing in one ear after attempting to see Chen.

Smith credited journalists for highlighting Chen's case and said: "I would earnestly ask them not to forget Mr Chen and his family, or his extended family and others who are risking their security and lives on his behalf."

"The story, unfortunately, is far from over," the New Jersey Republican added.