Washington, January 2 (Interfax-Ukraine) - U.S. Department of State has expressed concern over Gazprom's cutting off gas supplies to Ukraine.

"We are concerned that Gazprom has cut off gas sold to Ukraine," acting deputy spokesman for the U.S. Department of State Gordon Duguid said on Thursday in a statement on the dispute regarding gas delivery from Russia to Ukraine.

"The U.S. encourages Gazprom and Naftogaz to resume negotiations on an agreement that will maintain the reliability of gas delivery to Ukraine and Europe," the statement reads.

The U.S. urged Russia and Ukraine to resolve their dispute over the gas debt and the terms of their natural gas supply arrangements in a transparent, commercial manner.