"We will continue to cooperate fully with our partners in China to maintain and protect the warriors with the utmost care and reverence," the statement said.

According to an arrest affidavit filed last week, Rohana was attending a party held at the Franklin Institute on Dec 21 last year when he made his way into the museum's special exhibit "Terracotta Warriors of the First Emperor."

The FBI said that Rohana used a cellular telephone as a flashlight, looked at various exhibits displayed in the then-closed showroom, stepped up onto a platform supporting one of the statues, and took a selfie with it.

He put his hand on the left hand of the statue, appeared to break something off from the Calvaryman's left hand and put it in his pocket, and then left.

The Franklin Institute said on that night standard closing procedures were not followed by its external security contractor. It has reviewed its security protocol and procedures and taken appropriate action where needed.

"The Franklin Institute has multiple levels of security in place to ensure the safety of our artifacts, everything from personnel to technology that meets and exceeds museum industry standards," the museum said.

The incident has attracted great attention from both China and the United States amid calls for better protection of Chinese cultural artifacts on loan to other countries.

The cultural relics authority of China's Shaanxi Province said earlier this week that it will send two experts to repair the terracotta warrior statue.

The provincial cultural heritage department said that related U.S. departments should be held responsible for the damage, and guarantee the safety of the relics on display.

The Shaanxi Cultural Heritage Promotion Center has organized over 260 overseas exhibitions over the past 40 years, and has never come across a situation like this, said an official with the center.