Dissident Chinese artist Ai Weiwei said Wednesday that he has started returning money to his supporters after exhausting all legal channels to fight a massive tax bill that his backers saw as punishment for his activism.

After the government levied a $2.4 million tax bill on Ai's design firm last year, tens of thousands of Ai's supporters sent him money, some in the form of cash folded into airplanes flown over his gate.

Ai said the firm has started returning the money to his supporters after losing a final appeal in the tax case late last month.

"We have no more options to keep trying. We've done what we could, and the court's decision has been made. So we should repay the money," Ai said in a phone interview.

A sculptor, photographer and installation artist, Ai has used his art and online profile to draw attention to injustices in Chinese society and the need for greater transparency and rule of law. He was detained for nearly three months last year during an overall crackdown on dissent, and the tax case was filed after his release.

Ai and his company, Fake Cultural Development Ltd., accused the tax bureau of violating laws in handling witnesses, gathering evidence and company accounts.

The artist used the money his supporters sent him to pay a $1.3 million guarantee the tax bureau required before he was allowed to challenge the tax bill.

He said he was opposed to paying the remaining $1.1 million demanded by Beijing tax officials, but he wasn't sure if he would be forced to do so in the end.

The donations Ai received were rare for Chinese dissidents because of the threat of retaliation that comes with supporting high-profile government critics. In a commentary at the time, the state-run Global Times newspaper cited unnamed experts as saying Ai could be suspected of "illegal fundraising."

Ai had said that he would not treat the money from supporters as donations, but as loans that he would repay.