The National Museum of Korea made an official announcement Thursday that all 15 relics it has sent to the National Museum of China for an exhibition will be withdrawn unless a correction of facts on ancient Korean history is promptly made by the end of the day.

"If China does not accept our demands, we have no other choice but to immediately stop the Korean section of the exhibition, and push ahead with an early withdrawal of our relics," the statement read. The NMC had not responded so far to any of the NMK's letters demanding a correction, according to the statement.

On Tuesday, a domestic media outlet's Beijing correspondent found that the Goguryeo and Balhae kingdoms were missing from a chronological table of ancient Korean history at the NMC's special exhibition in Beijing.

The exhibition, titled “Auspicious Metals From the Orient: Ancient Bronzes of China, Korea and Japan,” which opened July 26 and runs through Oct. 9, was jointly organized by the national museums of the three countries.

In preparing for the exhibition, the NMK had sent a complete chronology of Korean history to the NMC on June 30. The NMK presumes that the material provided has been deliberately edited.

"We have made an urgent decision to send one of our museum's senior chief researchers and a senior specialist of international affairs by the end of this week at the latest," an official at the NMK told The Korea Herald on Thursday. "However, a 10-day quarantine period exists in China, so an immediate face-to-face contact is unlikely to happen at this point, which is another major problem that we are currently discussing.”

The Ministry of Foreign Affairs also spoke of the case at press briefings on Thursday, saying that the issue goes beyond matters within academia and will affect the two countries' relationship and the public perception of China.

Meanwhile, the NMK is also not free from public criticism on the issue, after it took more than six weeks for the issue to arise from an outside source.

When The Korea Herald asked how many relevant NMK staff members or representatives from Korea had attended the exhibition so far, the official answered none had, adding that all steps of preparation including the inspection of the condition and display of the relics had to be carried out solely online due to the pandemic.

The NMK has issued an official apology to the public, adding that the museum will strengthen measures to prevent a recurrence of a similar case.