By Chris Buckley
BEIJING (Reuters) - Chinese police say they have firm evidence the detained artist-activist Ai Weiwei avoided tax and he has begun "confessing," a Hong Kong newspaper under Beijing control said on Thursday, drawing a denunciation from his sister.
The Wen Wei Po newspaper said it had the firmest details yet of the accusations Chinese police are developing against Ai, whose secretive detention this month drew an outcry from human rights groups and Western governments, alarmed by the ruling Communist Party's campaign against dissent.
Burly, bearded Ai Weiwei was detained at Beijing airport on April 3.
He had a hand in designing the Bird's Nest stadium for the 2008 Beijing Olympics and has juggled an international art career with colorful campaigns against government censorship and political restrictions, often using the Internet.
His family has said the government's assertion that Ai is suspected of economic crimes is a pretext for hitting back against his activism.
Citing unnamed sources, the Wen Wei Po said investigators had gathered "a large amount of evidence that Ai Weiwei is suspected of avoiding taxes, and the sums are quite large.
"A source revealed to this newspaper that firm evidence has been collected about Ai Weiwei's suspected economic crimes," the newspaper said.
The Wen Wei Po is a Chinese-language paper published in Hong Kong by mainland authorities and is sometimes used to make Beijing's case on contentious issues. Hong Kong is a former British colony with its own administration and courts.
"As the investigation has deepened, the public security authorities have accumulated quite solid witness, documentary and circumstantial evidence and Ai Weiwei has had quite a good attitude in cooperating with the investigation and has begun to confess about the issues," the report said.
It also said Ai was suspected of bigamy and "spreading pornography on the Internet."
Ai's sister, Gao Ge, told Reuters police had given his family no information about his whereabouts or the accusations against him and the Hong Kong newspaper was being used to vilify him without giving Ai a chance to respond.
"This is not evidence. It's using a small paper to push their own position without giving Ai Weiwei any fair redress," Gao said by telephone.
"It's clearly against the law to hold him for so long without any notice to us."
The bigamy accusation, she said, was "absurd," and airing other charges without allowing Ai to respond was grossly unfair.
Ai, 53, is the most internationally prominent of dozens of Chinese dissidents, rights lawyers, activists and grassroots agitators detained or put in secretive custody since February, when fear of contagion from Middle East uprisings triggered a crackdown by China's domestic security apparatus.
On Thursday, Jin Bianling, the wife of Jiang Tianyong, a Beijing human rights lawyer taken into custody nearly two months ago by police, issued a written plea for information about his whereabouts and why he has been detained.
"It's been 54 days since he was taken away. He's never disappeared for so long before," Jin told Reuters by telephone.
"It's very hard not knowing anything about his situation."
The Human Rights Institute of the International Bar Association, which represents lawyers across the world, added to the criticisms of China's crackdown.
The London-based institute "expressed deepening concern over the intimidation, abuse and the worsening situation of human rights lawyers in China," in a statement.
It cited reports that Chinese lawyers "have been warned not to represent fellow lawyers and other detained activists or lobby on their behalf."
(Editing by Sanjeev Miglani)