Eight Ukrainian soldiers were killed and 16 wounded in clashes with the pro-Russian separatists in eastern Ukraine on Wednesday, security officials said.
"Over the past day there was one of the most intense bombardments of Ukrainian territory since the signing of the Minsk agreement," Ukraine's Security Council said.
Pro-Russian separatists said two of their fighters and a civilian were killed in Wednesday’s clashes.
Ukrainian military spokesman Andriy Lysenko said separatists used heavy artillery and attacks were intense near the towns of Svitlodarsk and Horlivka.
Russia and Ukraine have been at loggerheads ever since months of pro-EU demonstrations in Kiev forced former pro-Russian leader Viktor Yanukovych to flee the country in February 2014.
The West accuses Russia of supporting the separatist groups in eastern Ukraine, providing them weapons, while Russia denies the claims.
Nearly 1.4 million people have been internally displaced in Ukraine since the conflict began in March 2014. According to the UNICEF, at least 174,000 of them are children.
The conflict between Ukrainian forces and pro-Russian separatists have claimed over 6,000 lives.