Chinese cultural relics authorities have denied involvement in the sabotage of the 30-million-euro ($40 million) sale of two bronzes in Paris last week, while reiterating its stance that the items belonged to China.

They also said they did not know who was behind the bid for the relics until Monday, when Chinese antiques collector Cai Mingchao revealed he was the mystery bidder, Foreign Ministry spokesman Qin Gang said.

Cai later refused to pay for the bronzes as an act of patriotism.

While pointing out Cai's action was "not official", Qin said his ministry and the Ministry of Culture had repeatedly made clear China's stance against buying back the looted relics.

The bronze heads of a rabbit and a rat were sold to an anonymous telephone bidder during late French fashion designer Yves Saint Laurent's art collection's auction.

The heads were once part of a fountain featuring the Chinese zodiac's 12 animals at the Old Summer Palace. They were looted by invading Anglo-French troops when they razed the Old Summer Palace during the Second Opium War in 1860. Five of the bronzes had been returned to China while the other five's whereabouts are unknown.

The Foreign Ministry spokesman called for "attention to the core of the matter" when asked about the 44-year-old Cai's refusal to pay.

"The relics belong to China. They were looted by Western invaders and smuggled abroad," he said.

China had repeatedly demanded Christie's halt the auction and return the relics to their rightful owner. But a French court ruled the auction could proceed.

Cai referred to an order issued by the State Administration of Cultural Heritage (SACH) the day after the auction as further reason for not paying.

SACH requires documentation proving all artifacts Christie's shipped into and out of China are from legal sources. Because the two items had been officially deemed to have been illegally looted, Christie's would not be able to deliver them to Cai even if he paid, Cai said.

"As a Chinese, I must comply with the Chinese government's regulations. If the two auction items cannot enter China, of course, I won't pay," Cai said.

Auction laws state Cai could be required to pay commissions incurred by Christie's and compensate the firm for the price difference if the items are again put up for auction. The loss could easily add up to 10 million euros.

The National Treasure Fund, a non-governmental organization that retrieves looted treasures, supported Cai.

It said if he had not placed his bid, the two stolen bronzes would be lost forever, and the auction would have created a bad precedent for treasures scattered around the world.

Cai's justification of his move as a patriotic action had polarized the public.

Some view him as a national hero; others believe he was merely a renegade.

"It is the biggest default in auction history," Beijing Huachen Auctions general manager Gan Xuejun said.

He said the move might damage Cai's viability at art auctions.

Cai had passed Christie's financial screening because he had paid Sotheby's a record HK$116.6 million for a Ming Dynasty Buddha sculpture two years ago. He also owns an auction house in Xiamen, Fujian province.

"But Cai's political protest will put his name on the blacklists of auctioneers worldwide," Gan told China Daily.

"That means he will not be invited to future auctions, and his company would have difficulty financing overseas."

China Association of Auctioneers' chief lawyer Wang Fenghai criticized Cai for damaging Chinese people's global image and sabotaging their collective credibility, which had been built up over decades of reform and opening up.

But 74 percent of more than 260,000 netizens who participated in a sina.com survey supported Cai.

Some praised Cai for cleverly bringing the issues to a wider international audience, allowing Chinese people's discontent to be heard.

Many also said the high personal risks he accepted made him heroic.

Wang told China Daily Christie's still holds Cai's guarantee money and may claim it as a penalty.

In theory, Christie's could also organize another auction and require Cai to compensate for any price difference. But that would prove difficult in practice.

"A long legal and diplomatic wrangle is possible," he said.