A United Nations rights envoy has expressed concern over the South Korean government as it allowed the Myanmar ambassador to Seoul to attend an event promoting weapons systems in May, according to the envoy's letter on Wednesday.

Thomas Andrews, the special rapporteur on the human rights situation in Myanmar, made the remarks over Myanmar Ambassador Thant Sin's attendance at the event in Pocheon, 52 kilometers northeast of Seoul, on May 2 that demonstrated tanks and other weapons to foreign envoys from 18 countries.

"I am extremely concerned that your Excellency's Government reportedly extended an invitation to Thant Sin, who attended the event and was photographed raising his hand atop a K2 tank," Andrews wrote in the letter sent to the South Korean government on June 6.

"His reported participation in the event legitimizes an illegal and brutal military junta and raises doubts about the Republic of Korea's policy concerning arms transfers to the Myanmar military," he said, requesting clarification on the envoy's participation at the event.

The South Korean government sent a reply on July 26, explaining that it had invited all members of the Association of Southeast Asian Nations to the event.

"The invitation letters were transmitted to all ASEAN countries in accordance with established practice," it said. "The invitation does not mean any intention to grant arms transfers to Myanmar military or other entities in Myanmar."

South Korea has banned exports of military goods to Myanmar and halted bilateral defense cooperation after the country's military staged a coup against the civilian government in February 2021. (Yonhap)