Dissident Chinese artist Ai Weiwei was barred from a hearing Wednesday challenging a multi-million-dollar tax order against a firm he founded, he said, accusing authorities of trying to "crush" him.

Ai, an internationally acclaimed artist also renowned for his political activism, disappeared into custody for 81 days last year as police rounded up dissidents amid online calls for Arab Spring-style protests in China.

On his release, he was accused of tax evasion linked to Fake Cultural Development Ltd -- a company he founded, but which is legally registered in his wife's name.

Lawyers for Fake have lodged an appeal against the charges, which Ai says are politically motivated and have no basis. He has accused the tax bureau of failing to follow correct procedures in the case.

The 54-year-old said the bureau had never seen the full, original file brought against the company, which the police still holds, and Fake's lawyers had also not been allowed to review the evidence.

"How can you accuse someone but not give them the right to ask where this all came from?" he asked. "They are not professional and never intended to be professional, they just want to crush me."

In November, the Beijing tax bureau issued a bill for 15 million yuan ($2.4 million) in alleged back taxes and penalties, giving the artist 15 days to pay it or hand over an 8.45-million-yuan guarantee.

Ai was able to pay the guarantee -- needed by law to challenge the charge -- thanks to a wave of donations from supporters. In April, lawyers for Fake filed a lawsuit against the tax bureau, which was being heard Wednesday.

The court has until early August to rule on the case, Ai's lawyers said.

"They (police) have made clear their decision -- they said 'if you try to get to court, you will never get there'," Ai, who had planned to attend proceedings, told AFP.

"This is a very strange society in which on the one hand you try to put satellites into space and on the other hand you do not give the citizens a seat in the courtroom for them to see the process of justice," Ai said, referring to China's ongoing manned space flight launched Saturday.

Ai's assistant, Liu Yanping, said she had also been refused admission.

"I applied to attend court but they told me there was no more room," she told AFP by telephone.

The artist -- named the world's most powerful art figure by influential British magazine Art Review last year -- is renowned for his political activism, which has repeatedly angered the ruling Communist Party.

Large numbers of uniformed and plain-clothes police were deployed outside the courthouse in Beijing where the appeal hearing was held on Wednesday, in an indication of the sensitivity of the case.

Ai's wife Lu Qing, who is Fake's legal representative, was seen entering the court just before the hearing was due to begin at 0600 GMT Wednesday, but journalists gathered outside were ordered to leave the area.

Speaking to AFP at his studio in Beijing, where several police cars were also deployed, Ai said he had "no expectation" of the hearing.

Ai was released on bail on June 22, 2011, and barred from leaving Beijing for one year. The restriction expires on Friday, but it remained unclear whether he would be allowed to travel out of the capital.

He riled authorities with his investigation into the collapse of schools in the 2008 Sichuan earthquake and into a 2010 fire at a Shanghai high-rise that killed dozens.