"An agreement has been signed on the delivery of an extra 100,000-300,000 metric tons of coking coal a year. The supplies will be long-term," he said.

The documents were signed as part of a visit to South Korea by Russian Deputy Prime Minister Igor Sechin.

Yakutugol, a Mechel subsidiary, will be in charge of the deliveries.

The Russian steel giant currently supplies 1 million metric tons of coal annually to South Korean consumers, and the new agreement will increase the quantities by 10%-30%.

South Korea consumes 90 million metric tons of coal annually, all of which is imported, Mechel said.