U.N. human rights investigators have asked North Korea to clarify whether it has ordered troops to shoot on sight any trespassers who cross its northern border in violation of the country’s pandemic closure.

They were referring to a report by a news site focused on North Korea, Daily NK, which published a photo of what it said was a poster describing an August 2020 proclamation prohibiting acts that impede the closure of the northern border, shared mostly with China and a smaller section with Russia.

The poster describes a 1-2 kilometer buffer zone and says any person who makes an unauthorized entry to North Korea “shall be shot unconditionally.” It also says trespassers from other countries found on the North Korean side of the Yulu and Tumen rivers will be “shot without prior warning.”

In an 23 August letter posted on the website of the Office of the U.N. High Commissioner for Human Rights, the special rapporteurs expressed concern about the alleged order. They also asked North Korea to confirm reports that it made the distribution of South Korean cultural products or sexual content punishable by death under a law adopted last December.

Daily NK published photos of a document that supposedly spells out the law, aimed at stemming out “reactionary thought and culture.” The site said the law prescribes the death penalty for import or distribution of cultural contents from South Korea and other “hostile” nations such as the United States and Japan and does the same for sexual material.

The U.N. rapporteurs’ letter came weeks after activists from the South Korea-based Transitional Justice Working Group asked the U.N. to press North Korea over the alleged moves.

“We are concerned over the shoot-on-sight policy for unauthorized entry into the buffer zone along the northern border, as well as over the death penalty, without judicial guarantees, imposed on acts that appear to be guaranteed by international human rights law relating to the rights of freedom of opinion and expression and the right to take part in cultural life,” said the UN letter. It asked the North to provide information on the number of executions carried out under the alleged law against reactionary culture.

The letter was signed by Tomas Quintana, UN special rapporteur on human rights in North Korea; Morris Tidball-Binz, special rapporteur on extrajudicial, summary or arbitrary executions; Irene Khan, special rapporteur on the promotion and protection of the right to freedom of opinion and expression.

North Korea has never publicly acknowledged shoot-on-sight orders or executions over consumption of capitalist cultural content, and it wasn’t immediately clear whether the country would respond to the UN letter.

Army Gen. Robert Abrams, who was the top commander of U.S. troops in South Korea before retiring this year, told a forum last September that North Korea’s special forces along its border with China had “shoot-to-kill orders in place” aimed at preventing the virus from entering the country.

Later that month, North Korean troops shot and killed a South Korean government official who was found on a makeshift raft drifting near the sea boundary between the countries.

South Korea’s Unification Ministry, which handles affairs with the North, said Friday it couldn’t confirm the reports about the North’s extreme border controls and death penalties.

North Korea closed its border to nearly all traffic nearly from the start of the pandemic last year, banned tourists and flew out diplomats and other authorized foreigners in hopes of sealing itself off from the coronavirus.