North Korea imported South Korean-originated sodium cyanide last year, acquiring a toxic chemical that can be used to make deadly sarin nerve gas.

The Ministry of Commerce, Industry and Energy said Friday that a South Korean company shipped 107 tons of sodium cyanide, without an export permit, to a Chinese firm from June to September last year, which was then shipped to North Korea.

The ministry said the head of the company was later prosecuted and sentenced to one and a half years in prison with a two-year suspension for violating the country's trade law.

The ministry did not identify the names of the traders involved in the deal.

Separately, South Korea is investigating a report that a Malaysian company exported 40 tons of sodium cyanide, including 15 tons originating in South Korea, to the communist North in August.

Sodium cyanide is normally used to make fertilizers and in industrial plating. But treated with acids, it can be transmuted into sarin, a nerve agent that can cause loss of consciousness, paralysis and death.