The Russian Co-Chair of OSCE Minsk Group has rejected the invitation of his American counterpart to discuss the future of Nagorno-Karabakh, the Department of State's Bureau of European and Eurasian Affairs said on Tuesday, June 28.

"The U.S. OSCE Minsk Group Co-Chair spoke with her counterparts today to discuss the future of Nagorno-Karabakh," the Bureau said in a tweet.

"It's unfortunate the Russian Co-Chair did not accept the invitation. We look forward to the Minsk Group’s continuing work."

Russian Foreign Ministry Spokesperson Maria Zakharova said days earlier that Moscow doubts Washington's sincerity about readiness to cooperate with Russia within the OSCE Minsk Group co-chairmanship. Her comments came after U.S. Deputy Secretary of State Karen Donfried noted the United States was ready to work with Russia on achieving peace in Nagorno-Karabakh.