Two people were killed following a nitrogen leak at a LG Display factory about 40km north of Seoul, South Korea, on 12 January.

The company, which produces liquid crystal displays (LCD), said the incident also injured four others, with one of them in a critical condition.

One person died at the scene, while another died on the way to hospital.

The victims were employed by a LG contractor, and were carrying out regular repair and maintenance work at the time of leak that occurred after midnight at the P8 factory in Paju city. The factory produces LCD screens for large-size televisions.

The accident happened on the ninth floor of the plant, when the valve of a nitrogen gas cylinder was presumably opened by mistake, Korea Herald reported, citing firefighters.

LG Display said it regrets the deaths and will cooperate with authorities to find out the cause of the leak.

"We send our most heartfelt condolences and apologies to the deceased and will do everything in our power to help the injured recover as quickly as possible," the company said in a statement.

More than a dozen firefighters are remaining at the site to make sure there were no risks of another accident, Korea Herald added.

Seoul-headquartered LG Display is the largest LCD maker in the world. It manufactures and provides display panels in a broad range of sizes and specifications primarily for use in TVs, notebook computers, desktop monitors, tablets and mobile devices.

LG Display operates fabrication facilities in Korea and China and back-end assembly facilities in Korea, China, and Poland. The company has a total of about 53,000 employees operating worldwide.

Its shares are listed on the New York Stock Exchange and the South Korean Stock Exchange.