A close friend of celebrated Chinese artist Ai Weiwei says the artist-activist, who was released by police last week after nearly three months in confinement, has been ordered to pay nearly $2 million in back taxes and fines.

Chinese authorities said Ai confessed to tax evasion. But his family denies he evaded any taxes and his supporters, led by longtime friend Liu Xiaoyuan, insist he was arrested for his outspoken criticism of the authoritarian Beijing government and its ongoing crackdown on civil liberties.

Ai, who was ordered to remain in Beijing, has kept a low profile since his June 22 release, and has not commented publicly on his arrest or the charges.

The Associated Press on Tuesday quoted Ai's mother, Gao Ying, as saying authorities delivered the delinquent tax notice to her son Monday, and that he refused to sign a document acknowledging the debt.

The report also quotes Ai's wife as saying the artist is forbidden to discuss the conditions of his detention. She said plainclothes police follow Ai whenever he leaves his Beijing home.

The internationally acclaimed artist was arrested April 3, at the height of a Chinese crackdown on dozens of lawyers, dissidents and human rights activists. Weeks after launching the crackdown, authorities announced Ai's tax evasion charges.

Critics have described the government crackdown as a thinly-veiled attempt to stifle public protests like those in the Middle East and in North Africa earlier this year. Ai's arrest sparked protests at art venues in a host of Western countries and has been widely criticized by the United States and other Western governments.