FedEx Korea has issued an apology for delivering a live anthrax sample that the U.S. military accidentally sent to a U.S. Forces Korea lab five months ago, the country’s transport workers union said Friday.

The Korean unit of global air courier services firm offered an apology in an official document to the Korean Public Service and Transport Workers Union, which filed a complaint against FedEx Korea for failing to protect its workers and the public from hazardous materials.

“We apologize to FedEx employees here, customers and people in the country for causing anxiety over the issue,” the company said.

Earlier this year, the U.S. authorities confirmed that a U.S. military laboratory in Utah sent samples of live anthrax spores to 86 military labs in 20 U.S. states, Washington, D.C., and seven foreign nations including South Korea, where it went to Osan Air Base in Pyeongtaek, Gyeonggi Province.

FedEx Korea said it stopped delivering all types of parcels categorized as select agents by the U.S. Centers for Disease Control and Prevention and also stopped delivery services for goods from U.S. military labs in the U.S. since June.

“FedEx did not know what was in the package that the U.S. lab mistakenly sent. If we had known, we wouldn’t have taken the order,” the company said.

It added that no one was exposed to any danger during the delivery process and the workers who carried the anthrax sample didn’t show any health effects.

Employees of FedEx Korea belong to the transport workers’ union, an affiliate of the Korean Confederation of Trade Unions, the nation’s second-largest umbrella union.

The union withdrew the complaint after receiving the apology but it said that concerns remained over FedEx Korea’s safety measures.

By Park Han-na (hnpark@heraldcorp.com)