Beijing slammed auction house Christie's for selling two imperial bronze sculptures it says should have been returned to China and vowed Thursday to continue to hunt for and reclaim other similarly looted relics.

The State Administration of Cultural Heritage said the sale of two 18th century bronzes as part of an auction of art works owned by the late designer Yves Saint Laurent on Wednesday would affect Christie's interests in China.

The disputed fountainheads — heads of a rat and a rabbit — sold for $36 million at the Paris auction to an unidentified telephone bidder or bidders.

The auction "goes against the spirit of relevant international conventions and the international common understanding that cultural relics should be returned to their country of origin," the administration said in a statement.

Christie's auction of the two bronzes did not break any laws or international agreements, but China argued the relics are a part of its cultural heritage and should be returned.

The administration ordered tighter inspections of all cultural relics that Christie's seeks to bring in or out of mainland China.

The auction house said it regretted the administration's move to impose reprisal measures on Christie's and stood by the sale of the fountainheads, saying the pieces' legal ownership had been "clearly confirmed."

"We continue to believe that sale by public auction offers the best opportunity for items to be repatriated as a result of worldwide exposure," the firm said in a statement.

Christie's sales on mainland China are carried out through licensing partner Forever International Auction Company Limited, an auction house in Beijing. Its sales in 2008 totaled $6.2 million, according to a statement on Christie's Web site. In Hong Kong, sales last year totaled $452.3 million, it said.

The sculptures disappeared from the Old Summer Palace on the outskirts of Beijing when French and British forces sacked and burned it at the close of the second Opium War in 1860. Today, only ruins remain.

The cultural heritage administration said it will continue to recover looted Chinese relics through "all necessary channels."

China's frustrated efforts at securing the return of the bronzes underscores the challenges the country faces trying to recover numerous cultural objects stolen more than a century ago when plunder was a given in warfare.

A private group, China's Lost Cultural Relics Recovery Program, estimates there are more than 1 million relics outside the country, scattered in 200 museums in 47 countries and that 10 times as many could be in private collections.

China appeared unwilling to purchase the disputed bronzes pieces from their new owner or owners.

"That would give the 'stolen' goods a coat of legitimacy," the Old Summer Palace Museum said in a statement.

But the state conglomerate China Poly Group bought three Summer Palace fountainheads — the ox, monkey and tiger — in 2000 for about $4 million at auctions. The pig and horse heads were later both purchased by Chinese business figures and donated to China. The fates of the other five are unknown.