Artist and fierce government critic Ai Weiwei has turned the tables on China's Communist regime by transforming a crippling tax fine he says is designed to silence him into a huge wave of solidarity.

The painter, sculptor, architect and activist was a thorn in the side of the government even before he managed to pay a 8.5 million yuan ($1.3 million) bond thanks to money raised by some 30,000 Chinese people in record speed.

The burly artist disappeared into police custody for 81 days earlier this year. He was released in June, but on November 1 was ordered to pay 15 million yuan in back taxes levied against a company he set up.

Days later, a spontaneous online movement to help Ai began. Supporters sent him money orders, cheques, Internet transfers, and even rolled bank notes into balls and threw them over the walls of his Beijing studio.

Visitors flocked there -- some from as far away as Hainan island in the south, some 3,000 kilometres (1,860 miles) from the capital.

Within 10 days, 8.7 million yuan had been raised from artists, dissidents and ordinary Chinese, who accounted for the bulk of the donations.

Zhang Yaojie, a researcher at the China Academy of Art who is close to the dissident movement, said the government was "losing face" over the issue and "must regret its decision" to fine Ai.

"It didn't anticipate the strength of society's reaction in this Internet age," he said.

Ai, who denies that he evaded tax, has used the money raised from supporters to allow him to lodge an appeal against the fine, but pledged to pay it back when the case is over.

On Wednesday, he said the donations had made him realise that he was "not alone" in his struggle, calling the case a chance to "make the world understand what kind of system they are working with".

Authorities have apparently censored the Internet for information on the issue and a search for the term "Ai Weiwei" in China is blocked. But the Communist regime now finds itself in an awkward situation, analysts say.

"They (authorities) were hoping to reduce him to silence but on the contrary, they showed that there is support for Ai Weiwei," said Jean-Philippe Beja, a sinologist at the Paris-based research centre CERI SciencesPo.

"Ai Weiwei... has managed to transform this fine into an expression of defiance and into support for his cause."

Renaud de Spens, a Beijing-based Internet expert, said the outcome was a "huge kick in the teeth" for the government. "The regime tried to scare him, but it was not a good strategy," he told AFP.

One netizen named Shuxuediyijian joked online that the government had "failed", adding, "it didn't anticipate that Ai would receive donations and tell the whole world about it. How embarrassing!"

Even the state-run Global Times recently admitted "some donors say they see the donation as an act of voting" in a country with no real elections.

The wave of donations also shows that "there is a part of the population that supports critical stances and is not scared," Beja said, pointing to many donors who left their names with the money.

Ai -- who has been banned from leaving Beijing since his release -- denies the government's charge that he evaded taxes for years, insisting it is a politically motivated attempt to silence his vocal rights activism.

He is known for tallying the number of children killed in the 2008 Sichuan earthquake -- a hugely sensitive topic as many died in schools that were shoddily built and collapsed onto them, which many blamed on corruption.

"I think the (Beijing tax bureau's) decision was taken after police manipulation. That's why we asked for it to be revised," Ai's lawyer Pu Zhiqiang told AFP.

The Global Times newspaper has warned Ai could also be charged with "illegal fundraising" -- even though he did not instigate the donation wave -- saying he would "probably spend more time in politics than in arts in the future."

Until recently, Ai had been left relatively unscathed, despite his activism, thanks to his family background.

His father is the late Ai Qing, a famous poet who was in turn adored, disgraced and rehabilitated by the Communist regime. But not everyone is a fan of his son.

Accused by critics of being a "spoilt child" or arrogant, Ai -- a fluent English speaker who knows how to use the Internet and foreign media to his advantage -- is different to other Chinese dissidents.

But the man who was named the world's most powerful art figure by the influential Art Review magazine has acknowledged he is not immune to landing himself in hot water, as his secret detention proved.

"What I need is the ethical support of everybody," he said of the recent donation drive.

One netizen called Biaohanmoama wrote online that the 30,000 supporters would "keep on going with Fat Ai."

"There will be more and more people protecting him for being brave."