The wife and associates of Chinese artist Ai Weiwei appeared Thursday before a local taxation bureau to challenge charges that the artist has evaded hundreds of thousands of dollars in taxes.

Ai's wife, Lu Qing, appeared at the hearing with lawyers for the design company Beijing Fake Cultural Development, which is headed by Lu. The lawyers complain they cannot mount a proper defense without relevant tax documents, which were seized from Ai's home and office at the time of his arrest.

Ai is one of China's best known artists and has exhibited at the world's top galleries, receiving large sums of money for his work. The outspoken critic of government policies was arrested April 3 at the height of a crackdown on dissidents, during which dozens of lawyers and activists were arrested or disappeared from view.

Authorities eventually announced that Ai was being charged with tax evasion and then released him on bail late last month. The design firm was subsequently presented with a tax bill which, counting penalties, is reported to total almost $2 million.

The Associated Press quoted Lu as saying she and her lawyers were permitted during Thursday's hearing to see the documents that were seized in April, but not to keep copies. She said she was not sure what the next step will be.

Lu also told AP it is unclear when her husband might be able to leave the country to accept a post as lecturer at a university in Berlin.

Ai's passport has been seized and he has been ordered not to leave Beijing while his case is pending. He was also ordered not to give interviews to reporters under the terms of his bail.