Reuters reported that Turkey's regulatory competition board has opened an investigation into Turkish firms Erdemir and Borcelik and two local units of ArcelorMittal.

The board had opened a probe into steel companies to examine whether they had artificially raised prices, which have doubled within the last year.

Erdemir is Turkey's largest flat steel producer, followed by Borcelik. It has annual flat steel production capacity of 1 million tonnes. The two ArcelorMittal companies are ArcelorMittal FCE Celik Ticaret and a packaging firm.