The stake, totaling 12.3 million common shares, was bought from Cyprus-registered investment firm Aton International Ltd.
Severstal declined to specify the price of the deal, saying its subsidiary Bluecone Limited had represented the company in the transaction.
"Severstal Resurs believes the purchase of a 22% stake in Celtic, with its attractive mining assets in Russia and Kazakhstan, to be an excellent investment. This share acquisition is wholly consistent with Severstal-Resurs's strategy to diversify within mining, through alliances with internationally reputable partners," said Roman Deniskin, the CEO of Severstal-Resurs.
Celtic Resources Holdings Plc runs the Suzdal and Zherek gold mines in eastern Kazakhstan. The company also holds a majority stake in a project to mine copper and gold in the Chelyabinsk Region in Russia's South Urals. Celtic produced 1.9 metric tons of gold in 2006.
Severstal accounts for more than 16% of Russia's steel output. The company has production facilities in Russia, Italy, France, Great Britain and Ukraine.