The newspaper reported that the Chinese Embassy in Moscow issued a warning on Sunday, after they discovered fake negative nucleic acid test results for the novel coronavirus, which the government requires passengers take within five days of flying from Russia to China.

According to the Post, the Chinese Embassy released a statement on their WeChat account, saying that those who forged negative tests were under investigation and would “bear corresponding legal responsibilities.”

The embassy also said that the passengers caused great harm to the health and safety of the other passengers and crew on the flights, as well as undermining China’s domestic epidemic prevention work.

The novel coronavirus, which causes the respiratory disease COVID-19, has infected over 619,000 people in Russia, placing the country third for cases following the U.S. and Brazil. Russia has also reported at least 8,770 deaths, according to a tracker provided by Johns Hopkins University.

In China, where the virus originated, there are currently over 84,000 confirmed cases of the new virus and at least 4,641 deaths.

In late-January, Russia first closed its borders with China, as the virus was nearing its peak and shortly after, in late-February, they banned entry for all Chinese citizens. A few months later, in April, when virus cases increased in Russia, but decreased in China, the Asian country followed similar protocols and closed its border with Russia. That policy remains in place.

The fake test results come as Beijing officials search for the origin of a second outbreak of the novel virus, which has infected 249 residents since it was detected in the Chinese capital’s largest supermarket on June 11.

According to the Post, members of China’s Center for Disease Control and Prevention (CDC) have struggled to find the source of the second outbreak in cases. The newspaper reported that Zhang Yong, assistant director for China’s CDC said that the strain of the virus found in Beijing originated in Europe, but Wu Zunyou, chief epidemiologist for the CDC, said that while the genetic material of the virus showed a European strain, the same strain was also common in Russia and the U.S., making it difficult to determine where it came from.

Newsweek reached out to the Chinese embassy for comment but did not receive a response in time for publication.