Experts on Chinese art in the US said they don't believe that the theft of a thumb from a 2,000-year-old terracotta warrior statue on loan to a Philadelphia museum will deter the exchange of artifacts China.

"I believe the cultural exchange activities still will continue," Willow Weilan Hai, senior vice-president and director of the China Institute Gallery in New York, said in an email.

According to an arrest affidavit the FBI submitted in federal court last week, Michael Rohana, 24, from the state of Delaware, allegedly sneaked into the terracotta warrior exhibit at the Franklin Institute during an after-hours event on Dec 21 and broke off the left thumb of the statue after taking a selfie with the statue.

Museum staff didn't notice the missing thumb until Jan 8. The FBI said it traced it to Rohana five days later and recovered the thumb in a desk drawer at his home.

Rohana was charged last week in Philadelphia with theft of an artwork from a museum, concealment of the artwork and interstate transportation of stolen property. He was released on bail.

"We call on the United States to severely punish those who have done [this]," Shaanxi Provincial Cultural Relic Exchange Center's director said in a statement. The Shaanxi Cultural Heritage Promotion Center, which loaned 10 of the terra-cotta sculptures to the Franklin Institute, said it was the first such incident in more than four decades of organizing overseas exhibitions.

"Of greater concern is the lax oversight during an evening event and the Franklin Institute, a highly reputable institution, will undoubtedly professionally address this issue so there are no long-term repercussions on US and China relations concerning the loan of priceless works of art," Lark Mason, former chairman of Asia Week New York and the owner of iGavel, a New York-based appraisal service and auction house specializing in Asian and Chinese art, said in an email.

"It reveals that security is an issue in the museum system, which means the museum is not entirely secure. It is an alarm to all the museums to be extra alert in receiving (and) displaying rare treasures,'' said Hai. "Maybe the procedure for approval, checking on a display plan and security will be tightened in the future," she added.

"As a scholar, I feel it would be regrettable if this led to a decrease in cultural exchange, for the benefits of such an exchange far outweigh the risks. Works from American museums sometimes suffer damage during loans for exhibits, and this is always unfortunate, but such losses are rare," said Martin Powers, the Sally Michelson Davidson professor of Chinese Arts and Cultures at the University of Michigan in an email.

"Most Americans have very little knowledge of Chinese history and culture and much of what they think they know is error ridden. I find that many people develop a more positive impression of Chinese history after attending an exhibition of artifacts from China," Powers said.

The cultural relics authority of Shaanxi province has sent two experts to repair the statue. Discovered in 1974 by farmers in China, the underground army of nearly 8,000 life-size terracotta figures is considered one of the greatest archaeological finds of the 20th century. The full-size statues were part of the baked earth army sculpted by artisans for decades so that they could be buried with Qin Shi Huang, the first emperor of China (260-210 BC), and serve him in his afterlife.

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