Hillary Clinton in her new book passionately defended her role in the release of Chinese dissident Chen Guangcheng, criticizing Republican assertions that the United States pressured him.

In "Hard Choices," the former secretary of state and potential presidential contender credited US efforts to nurture relations with China with allowing an atmosphere in which Beijing allowed the blind-since-childhood activist to move to the United States.

Clinton credited her assistant secretary of state for East Asia, the flamboyant academic Kurt Campbell, with his role in the episode and said at one point he volunteered to resign when the talks almost fell apart.

Chen, who enraged authorities by exposing forced abortions and sterilizations under China's one-child-only policy, escaped from house arrest in April 2012 and fled to the US embassy days ahead of a visit by Clinton.

The United States arranged an agreement with Beijing in which Chen would be allowed to study in China, receive medical treatment and file complaints over the beatings he said he suffered.

The deal triggered an uproar in Washington, as Chen told a congressional hearing by telephone he was afraid for his safety by remaining in China.

"It was like throwing fuel on the political fire," Clinton said of Chen's remarks, saying that her aides had negotiated the initial deal in accordance with the activist's own wishes.

"While Chen seemed to be talking easily with every reporter and activist from Beijing to Washington, no one at the embassy could reach him on the cell phone that, ironically, we had provided," Clinton wrote.

Clinton said she moved to counter "breathless news reports" that the United States refused him asylum and blamed "election-year politics," criticizing Republican presidential candidate Mitt Romney whose campaign said that the Chen case marked "a dark day for freedom."

Clinton said that Dai Bingguo, then state councilor and considered the force behind China's foreign policy, had told the US side that they "had made a big mistake in trusting Chen" and called him a "manipulative criminal."

But Clinton said she wanted to comply with Chen's wishes and told Dai she faced a "political firestorm" over the case.

Clinton said her deputy, William Burns, initially persuaded Chinese diplomats to resolve the case by arguing it was best to "put this whole incident behind us" so that top leaders could hold scheduled US-China talks without getting involved.

Chen ultimately came to the United States to study and has emerged as an outspoken critic of China.