Mirotvorets is a Kiev-based website that publishes the personal information of individuals that it deems anti-Ukraine, effectively threatening their well being and even their lives.
"We, therefore, ask you [Guterres] to take necessary steps to draw the attention of the Ukrainian authorities to the criminal activities of the Mirotvorets project and force them to close it," the letter said.
Mirotvorets has so far listed more than 240,000 people, some of which are children, and published their details, including their address, telephone numbers and other information, the letter said.
The Russian mission noted in the letter that the situation of exposing people has worsened due to the lack of United Nations involvement.
The threat to the well being of at least 327 children listed on the website is acute too, according to research by a Russian non-governmental organizations that deal with children.
The Russian mission to the United States has raised the issue twice - in October 2021 and in January - with the United Nations Children's Fund (UNICEF) leadership. The mission noted that the engagement with UNICEF was very formal and did not change the situation.