BEIJING — Outspoken artist Ai Weiwei said Tuesday that Chinese authorities are demanding he pay $2.4 million in back taxes and fines in a new show of government pressure on the dissident detained for nearly three months earlier this year.

The Beijing Local Taxation Bureau gave the artist notice Tuesday that he owed more than 15 million yuan (US$2.36 million), after serving a similar notice in June for a smaller amount, Ai said in a phone interview.

The new notice gave him around 10 days to make the payment, without saying what might happen if he failed, he said.

Ai said he would not pay until police returned account books confiscated from his Beijing Fake Cultural Development Ltd. design company and allowed him to meet with his former office manager and accountant.

"We can pay this money, but we need to know why we have to," he said. "We cannot just unwittingly hand over a sum of money. This would be irresponsible toward the country."

Authorities have not commented on the issue, and calls to the local tax bureau rang unanswered while Beijing's Public Security Bureau did not respond to a faxed list of questions.

Ai was detained secretly without charges for 81 days this year, sparking an international outcry among artists, politicians, activists and Western leaders who called it a sign of China's deteriorating human rights situation. Police also raided his studio and confiscated account books.

His family and supporters have said he is being punished for speaking out against the country's Communist leadership and social problems. Activists have called the government's tax evasion claims a false pretence for Ai's detention.

"Accounts for tax purposes should be investigated by the tax bureau, not the police," Ai said Tuesday. "Police should not be taking me away to a place that no one knows for 81 days to investigate taxes."

After his release in June, the tax bureau served a notice seeking about 12 million yuan (US$1.85 million) from him. But his design firm challenged the bill and were told by Chinese authorities that the company had not paid corporate taxes for a decade.

Ai, who has shown his art in London, New York and Berlin and earned huge sums from sales, said he was most concerned that authorities were misusing the law in going after him.

"If you want to hurt one person, to hurt me, that's all right," he said. But "when you hurt the law, it hurts the country and everybody in it."