A U.S.-based Chinese scholar and democracy campaigner has returned to the United States after serving a five-year prison sentence in China on charges of illegally entering the country to spy for Taiwan.

Friends of Yang Jiangli, a former Tianamen Square activist and permanent U.S. resident, tell VOA Mandarin Service that he flew out of China late last week, following months of pressure for his release from the Bush administration and the U.S. Congress. The dissident's supporters say Yang was abused by prison guards and suffered a minor stroke during his detention.

A San Francisco-based Chinese dissident web site and relatives said Yang arrived in the U.S. city of Boston late Saturday, accompanied by a U.S. diplomat from the U.S. embassy in Beijing.

More than 100 U.S. lawmakers sent a letter to President Bush last year asking him to lobby Chinese President Hu Jiantao for Yang's release.

Yang is expected to address a news conference Tuesday in Washington.

Yang is the chairman of a Boston-based think-tank, the Foundation for China in the 21st Century. He moved to the United States after the pro-democracy demonstrations at Tianamen Square were crushed by Chinese troops 1989.

Some information for this report was provided by Reuters.