A Chinese expert on international cultural relics law said Friday that a proposed lawsuit seeking the return of two looted Chinese relics to be auctioned in Paris is unlikely to succeed.

A team of 81 Chinese lawyers have written to Christie's auction house in an effort to stop the sale of the Qing Dynasty (1644-1911) bronze rabbit and rat head sculptures. They have also written to Pierre Berge, current owner of the sculptures, asking him to return the relics to China.

The team said they would sue Pierre Berge in France if their letters failed to receive "positive feedback". Christie's, which has scheduled the auction from Feb. 23 to 25, would be named in the lawsuit as a third party.

"With full respect to their sincerity and patriotism, I think there is little chance of them winning the lawsuit," Wang Yunxia, a professor of cultural relics law at Renmin University in Beijing, told Xinhua.

China and France signed the 1995 Unidroit Convention on Stolen or Illegally Exported Cultural Objects, which is intended to facilitate the restitution and return of stolen cultural relics.

But Wang said the fact that the convention could not be applied retroactively was a major obstacle. "That means the convention applies only to cultural objects that are stolen or illegally traded after the convention takes effect," she said.

The United Nations Educational, Scientific and Cultural Organization (UNESCO) in May 2000 invited Wang and seven other international experts to draft the Declaration of Principles relating to Cultural Objects Displaced in Connection with the World War Two.

The two bronze head sculptures formed part of the zodiacal clepsydra that decorated the Calm Sea Pavilion in the Old Summer Palace of Emperor Qianlong (1736-1795). They were stolen when the palace was burnt down by Anglo-French allied forces during the Second Opium War in 1860.

"So far, I haven't seen any international conventions or laws that could be applied to the relics dating back that far (to the Qing Dynasty)," she said.

However, Wang also said even though the convention stipulated time limits, it also says it did not in any way legitimatize any illegal transaction that had taken place before its entry into force, nor limited any right of a state or other person to make a claim under remedies available outside the framework of the convention.

"The convention might not be directly applicable in the lawsuit, but it has a strong moral binding force," she said. "The court in France would face a strong moral consideration in handling the case."

She said if the lawyers did win the case, the verdict "would be made due to moral concerns rather than law and regulations".

The sculptures, belonging to the Pierre Berge-Yves Saint Laurent (YSL) Foundation, were put up for auction by Pierre Berge. They are expected to fetch 8 million to 10 million euros (about 10.4 million to 13 million U.S. dollars) each.

The Chinese lawyers had reportedly had trouble finding an appropriate plaintiff and raising enough money for the lawsuit.

But Liu Yang, chief lawyer of the team, told Xinhua this week that those problems were gone as the Global Aixinjueluo Family Clan, a civil society registered in Hong Kong, has agreed to be the plaintiff. Aixinjueluo is the clan name of the emperors of the Qing Dynasty.

A company in Shenzhen in south China agreed to donate 400,000 yuan (58,823 U.S. dollars) to the lawyers to cover the legal cost, Liu said.

China's State Administration of Cultural Heritage (SACH) has openly voiced its objection to the auction of any looted Chinese relics.

Song Xinchao, director of the museum department with the SACH, said the auction of the Chinese cultural relics, which were illegally exported from China, would offend the sensibilities of the Chinese public.

"We hope Christie's and the parties concerned will seriously reconsider," Song was quoted as saying by the Guangming Daily.

So far, five of the 12 bronze animal heads have been returned to China. The whereabouts of five others are unknown.

The U.S. auction house Sotheby's tried to put a bronze horse head under the hammer in 2007. But Macao billionaire Stanley Ho pre-empted the auction by purchasing the relic for 69.1 million Hong Kong dollars (9 million U.S. dollars), and donated it to the Chinese government.