Ukraine's President Volodymyr Zelenskiy says he has spoken with his Russian counterpart, Vladimir Putin, after four Ukrainian soldiers were killed in shelling in eastern Ukraine.
"I called him urgently. I told him that this brings us no closer to peace," Zelenskiy said during a news briefing in Kyiv, adding that he had urged Putin to ask the Moscow-backed separatists to "stop killing our people."
He also said Putin had promised him something, details of which would be disclosed later.
The Kremlin has not commented on the phone call.
Ukraine's Defense Ministry said in a statement on August 6 that the separatists had opened fire at Ukrainian military positions in the Donetsk region earlier that day, using grenade-launchers, machine guns, and assault rifles.
"As a result of the enemy's attacks today, according to the information in our possession, four of our heroes sustained injuries, to which they succumbed," the statement said.
It was the highest daily casualty toll in the Ukrainian conflict since a truce was agreed nearly three weeks ago.
Since April 2014, more than 13,000 people have been killed in the conflict.
A cease-fire agreement, involving Russia and Ukraine and brokered by France and Germany, ended major conflict in eastern Ukraine in 2015, although regular small-scale clashes have continued to cost lives.