A Chinese cultural official is calling for stringent punishment for an American man accused of snapping off a thumb from an ancient Terracotta Warrior at a museum exhibit in Philadelphia in December.

On Monday, Wu Haiyun, the director of the Shaanxi Cultural Heritage Promotion Center, the group that loans the Terracotta Army to overseas museums, told CCTV that a “serious protest” had been lodged.

“We ask that the US severely punish the perpetrator,” said Wu, who earlier said he was “shocked and enraged” by the incident and criticized the Franklin Institute for not notifying him sooner.

The center, which said that nothing this “vicious” has happened previously in more than 260 overseas exhibitions in 60 countries over 40 years, will dispatch two professionals to the US to repair the damaged statue, one of 10 on loan to the museum.

Michael Rohana, 24, has been charged in the theft. He also took a selfie with the statue before allegedly snapping off the part at an after-hours party at the museum, authorities said.

Rohana has been charged with theft of a major artwork from a museum, concealment of major artwork stolen from a museum, and interstate transportation of stolen property, according to an affidavit filed on Friday in federal court. He was released on bail.

The thumb was eventually recovered at his home, authorities said.

“This was a deplorable act, and we share in the condemnation of this crime as expressed by our partners at the Shaanxi Cultural Heritage Promotion Center,” Stefanie Santo, a spokeswoman for the Philadelphia museum, said in a statement, according to philly.com. “We will continue to ... maintain and protect the warriors with the utmost care and reverence.

“We have thoroughly reviewed our security protocol and procedures and have taken appropriate action where needed,” she said.

The thumb originally was broken when the Terracotta Warrior was excavated, but the fracture had been repaired before the statue went on exhibition in the US, the center said. The thumb was snapped from the exact spot it was repaired.

Rohana was a guest at an “ugly sweater” party at the museum on Dec 21 when he went into a closed exhibit of the statues, authorities said.

The thumb came from the life-size clay soldier known as “The Cavalryman”, on display through March 4.

The soldier is part of a Terracotta Army that provided after-life security at the burial complex of China’s first emperor, Qin Shi Huang.

The suspect walked into the darkened exhibit during a “Science After Hours” party, according to an affidavit by the FBI, USA Today reported. An door was closed but apparently unlocked.

A surveillance video shows the guest alone with “a priceless part of China’s cultural heritage”, FBI Special Agent Jacob Archer, a member of the FBI’s Art Crime Team, said in the affidavit.

Archer’s affidavit, filed Friday in federal court in Philadelphia, said Rohana of Bear, Delaware, at one point “placed his arm around that sculpture and took a photograph of himself with the sculpture”, Archer said.

Rohana “appeared to break something off the Cavalryman’s left hand and put it in his left pocket”, said the agent.

A museum staffer noted the thumb’ was missing on Jan 8.

When Archer interviewed Rohana at his family’s home on Jan 13, the suspect led the agent to his bedroom, where the stolen thumb was in a desk drawer, according to the affidavit.

Hu Yumeng and Heng Weili in New York contributed to this story.

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