Clashes between Ukrainian forces and Moscow-backed rebels left two more dead in a flash point town on Friday and four others elsewhere in bloodshed that has prompted the US to condemn Russia's "aggressive" stance.
The latest reports from both sides put the death toll in fighting since Sunday in the eastern war zone to 32 -- a figure that has not been reached since the height of the war in 2014 and 2015.
US Ambassador to the United Nations, Nikki Haley, blamed Russia on Thursday for the surge of violence in the eastern Ukraine since late January.
"I consider it unfortunate on the occasion of my first appearance here I must condemn the aggressive actions of Russia," Haley said, making her first public remarks inside the Security Council since being sworn in as the United States' representative last month.
"It shouldn't happen, or be that way. We do want to better our relations with Russia. However, the dire situation in eastern Ukraine is one that demands clear and strong condemnation of Russian actions."
The US criticism of Moscow will be welcomed in Kiev because it is particularly worried about losing Washington's support as new President Donald Trump seeks to mend ties with Russia's Vladimir Putin.
But Kremlin spokesman Dmitry Peskov on Friday dubbed Ukrainian actions as 'reckless.'
"The main thing is to persuade Kiev to drop such reckless actions which are capable of undermining the Minsk peace process," Peskov told a conference call with reporters.
Ukrainian forces and rebels have been exchanging mortar and rocket fire near the frontline town of Avdiivka just north of the pro-Russian rebels' de facto capital of Donetsk.
The Ukrainian army said the latest fatal victims were a local woman and an emergency worker in Avdiivka. The toll in the industrial town now stands at 27.
Authorities said that three soldiers had also been killed in other parts of eastern Ukraine in which pro-Russian insurgency has raged since April 2014.
The rebels also said that shelling by the Ukrainian army had reportedly killed two civilians in Donetsk.
The conflict began less than two months after Ukraine ousted its Russian-back leader in April 2014.
Moscow responded by annexing Ukraine's Crimea peninsula in March 2014 and then allegedly plotting the eastern insurgency to keep Ukraine under its thumb after its tilt toward the West.