A Chinese dissident who wrote a critical book about Premier Wen Jiabao has fled into exile in the United States, saying Thursday that he faced physical abuse and restrictions on publishing.

Yu Jie, who in 2010 published in Hong Kong the book "Wen Jiabao: China's Best Actor" despite threats of jail time, flew Wednesday to Washington with his family after quietly leaving Beijing, a member of a rights group said.

In an interview with Radio Free Asia, Yu said that he has come under intensifying pressure since fellow dissident Liu Xiaobo won the Nobel Peace Prize in 2010 and was "subjected to torture."

"For the better part of the past year, I was deprived of my freedom and under surveillance," the 38-year-old told the US-supported broadcaster.

Yu said that Chinese authorities banned him from further publishing overseas and of his freedom to practice his religion. He is a member of an unauthorized Protestant church.

"I felt that, as a writer and as a Christian, I no longer had any freedom to express myself and to practice my religion. So I chose to come to the United States, where I can live freely," Yu told Radio Free Asia.

Yu said he expected to spend "a relatively long time" in the United States and would not stop writing.

The US State Department, in a brief statement in response to a question, said that it was aware of reports of Yu's flight into exile but has "not had any contact with Chinese officials about his reported arrival."

Yu fled to the United States just as Treasury Secretary Timothy Geithner was in Beijing. China has generally rebuffed US calls to free dissidents and Geithner was focused on economic issues and on drumming up pressure on Iran.

Yu frequently visited the United States but always returned to China. In 2010, he told AFP in Los Angeles that Liu's Nobel would improve conditions for other dissidents as China "will think twice before they put another person like Liu Xiaobo in prison."