Russia should end the fighting and implement Minsk agreements in Donbas, the official said.

United States Special Representative for Ukraine Negotiations Kurt Volker has accused Russia of worsening the situation in Donbas, eastern Ukraine, including the live of its Russian-speaking residents.

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"For the last five years Russia's fighters and proxies have made life worse for the people in Donbas including the Russian-speakers it claims to care about," he wrote on Twitter on May 10.

"Russia should end the fighting, implement Minsk agreements, and allow reconstruction and reintegration of Donbas back to Ukraine's control," he added.