The mother of detained artist Ai Weiwei said yesterday that authorities in China were trying to silence her son with their investigation of his alleged economic crimes, which she called “unacceptable”.

In a one-paragraph dispatch, the official Xinhua news agency said Mr Ai, who was detained on Sunday at Beijing’s international airport while awaiting a flight to Hong Kong – was being investigated for suspected economic crimes.

“I don’t believe these charges of economic crimes ... I don’t think this is the reason they have taken him away,” Gao Ying, who is nearly 80, said in a telephone interview.

“This is unacceptable, it is not right.”

Mr Ai, a widely respected artist and the son of a poet revered by China’s early Communist leaders, helped design the Bird’s Nest Olympic Stadium for the 2008 Beijing Games, but has since irritated the government with his social activism.

He probed the collapse of schools in the 2008 Sichuan earthquake, looked into a Shanghai high-rise fire last November that killed dozens, and says police beat him when he tried to testify on behalf of another activist in 2009.

“What has happened is not right. He must have his voice, his work, it is not right that they take him away like this and accuse him of being a criminal,” Mr Ai’s mother said between sobs.

“He must be treated fairly. He has the right to voice his views. The actions of the state show that someone wants to take his voice away,” she said.

“Ai Weiwei is not a politician, he has no political background. What he does, he does for the nation and for the people – he is not doing this for himself.”

On Sunday, police raided the Beijing studio of the 53-year-old artist – a burly man with a distinctive wispy beard whose work is currently on display in London’s Tate Modern gallery.

Since he was taken into custody, no charges have been filed against him and the police have so far refused to confirm why he was detained.

The police silence prompted Ms Gao to post a missing person’s notice on the internet on Wednesday, urging people with knowledge of Mr Ai’s disappearance to come forward, she said.

“They have to inform us why they have taken him away,” Ms Gao said.

“There are a lot of people who will support me, there are a lot of people who will back us. We need justice.”

Meanwhile, China warned the international community that it had “no right to interfere” in the case of outspoken artist Ai Weiwei.

Foreign ministry spokesman Hong Lei confirmed a state media report that Mr Ai, an avant-garde artist known as much for his work as for his brash criticism of China’s communist leaders, was under investigation after being detained on Sunday.

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