"The United States is deeply concerned with the recent spike in violence in eastern Ukraine around Avdiyivka-Yasynuvata," Acting Spokesperson Mark Toner said in a press statement in Washington, D.C., on January 31, 2017.

Since January 28, the OSCE's Special Monitoring Mission has reported a dramatic increase in fighting, including with heavy artillery and other weapons proscribed by the Minsk agreements.

Read alsoOSCE monitors report civilian casualties in AvdiyivkaThe fighting has caused dozens of Ukrainian military casualties and 10 civilian casualties. It has also left 17,000 civilians, including 2,500 children, without water, heat, or electricity.

"To avert a larger humanitarian crisis, we call for an immediate, sustained ceasefire and full and unfettered access for OSCE monitors. We also reaffirm U.S. support for full implementation of the Minsk agreements," the press statement said.