Ukraine and Russia blamed each other on Tuesday for a surge in fighting in eastern Ukraine over recent days that has led to the highest casualty toll in weeks and cut off power and water to thousands of civilians on the front line.
The Ukrainian military and Russian-backed separatists accuse each other of launching offensives in the government-held industrial town of Avdiyivka and firing heavy artillery in defiance of the two-year-old Minsk ceasefire deal.
Eight Ukrainian troops have been killed and 26 wounded since fighting intensified on Sunday - the heaviest losses for the military since mid-December, according to government figures.
"The current escalation in Donbass is a clear indication of Russia's continued blatant disregard of its commitments under the Minsk agreements with a view of preventing the stabilization of the situation and achieving any progress in the security and humanitarian spheres," Ukraine's foreign ministry said in a statement.
The peace deal was agreed in February 2015, but international security monitors report ceasefire violations on a daily basis, including regular gun and mortar fire.
The latest clashes mark the first significant escalation in Ukraine since the inauguration of U.S. President Donald Trump, whose call for better relations with Moscow has alarmed Kiev while the conflict remains unresolved.
Ukrainian authorities said they were prepared for a possible evacuation of Avdiyivka's 16,000 residents, many of whom have little or no access to electricity or water after shelling from the separatist side hit supply infrastructure.
Meanwhile Kremlin spokesman Dmitry Peskov said Ukrainian government troops had launched a deadly attack on pro-Russian rebels across the Avdiyivka front line on Monday.
"Such aggressive actions, supported by the armed forces of Ukraine, undermine the aims and the task of realizing the Minsk accords," he said, accusing the Ukrainian authorities of organizing the offensive as a ruse to try to distract attention from domestic and other problems.
Close to 10,000 people have been killed since fighting between Ukrainian troops and rebels seeking independence from Kiev erupted in April 2014.
Ukraine and NATO accuse the Kremlin of supporting the rebels with troops and weapons. The United States and have imposed sanctions on Russia over the conflict, as well as for its annexation of Crimea.