An open letter to the World Health Organization demanding an investigation into U.S. Fort Detrick and reports of it being the source of the coronavirus has been signed by over 5 million Chinese online users.

Analysts said while the petition may not be a serious demand, it does reflect the outrage of the Chinese people toward the politicizing of the pandemic and the shifting of the blame by some U.S. officials. The number of signatures on the open letter has continued to rise. It surpassed the 5 million mark Thursday.

The letter was drafted by a group on social media. It asked the World Health Organization to investigate the U.S. Army's Medical Research Institute of Infectious Diseases at Fort Detrick. The letter was posted on WeChat and Weibo.

Chinese Foreign Ministry representative, Zhao Lijian, said the rising number of signatories is a clear representation of the anger felt by the Chinese people over the political manipulation of some in the U.S. involving the origins of the virus.

Similar to the Wuhan laboratory, the facility in Fort Detrick also stores some of the deadliest and infectious viruses in the world - including smallpox, Ebola, SARS and MERS. The letter asked the World Health Organization to put more focus on these types of facilities to prevent another outbreak.

The letter said leaks or lapses in security at the facility could threaten humanity. It also expressed concerns about whether the coronavirus that triggered the pandemic was related to the Fort Detrick lab.

The letter cited an incident in July 2019, when the U.S. Centers for Disease Control and Prevention issued a "cease and desist order" to the lab at Fort Detrick. The letter said that while the lab reasoned that the order was because of "ongoing infrastructure issues," some have questioned whether it was a possible leak.

Last week, the World Health Organization proposed the second phase of studies into the origins of the pandemic in China. The organization said it plans to make another audit of the laboratories and wet markets in Wuhan. It also called on authorities to be more "transparent" and to help it determine the true origins of the disease.