The European Union says that increasing attacks in government-held areas in eastern Ukraine violate February's cease-fire deal that was agreed in Minsk.
"The renewed escalation of the conflict...as a result of attacks on several government-controlled areas today and in the night of 10 August on Starohnativka violates the spirit and the letter of the Minsk Agreements," the EU's External Action Service said in a statement on August 11.
Also on August 11, the Russian Foreign Ministry said the situation on the front line had deteriorated in recent days and urged Kyiv to end its "irresponsible actions" in eastern Ukraine.
On August 10, the Ukrainian military reported the heaviest shelling by pro-Russian separatists since the Minsk truce was signed in February.
The fragile Minsk cease-fire is marred by daily violations.
More than 6,400 people have been killed in the military conflict between Ukrainian armed forces and pro-Russia separatists in parts of Ukraine's eastern regions of Luhansk and Donetsk since April 2014.