Worst fighting in east Ukraine since 2015 sees 33 killed
International monitors have strongly urged both sides in eastern Ukraine to stop fighting as heavy artillery and rockets continue to pummel residential areas.
At least 33 people including civilians have been killed and several dozen injured in fighting this week between government forces and Russia-backed separatist rebels.
It marks the worst violence in the region since 2015.
The death toll in the fighting that began in April 2014 has now exceeded 9,800, according to UN figures and a tally of recent fighting.
"Unacceptable! ... Sides have to stop fighting!" the monitoring mission of the Organisation for Security and Cooperation In Europe (OSCE) said on Facebook.
While the warring sides have regularly exchanged gunfire despite a February 2015 peace deal brokered by France and Germany, this week has seen a sharp spike in hostilities.
Fighting has raged around the government-controlled town of Avdiivka, just north of the main rebel stronghold of Donetsk, catching residential areas in the crossfire.
"We have seen on both sides an incredible amount of ceasefire violations," said Alexander Hug, deputy head of the OSCE's monitoring mission.
Each side blamed the other for the upsurge of violence, but the Ukrainian military says its troops have gained some ground.
Heavy weapons could be seen on both sides of the front line, in clear violation of the 2015 peace deal.
"We have seen the whole range of heavy weapons in the area here, starting from the smaller calibre mortars to larger calibre artillery to multiple launch rocket systems in the areas where they shouldn't be," Mr Hug said.
"We have seen them inside Avdiivka. We have seen them in Yasynovata. We have seen them in Donetsk city."
Ukrainian president Petro Poroshenko has cast the outburst of fighting as an argument for continuing Western sanctions imposed on Moscow for its actions in Ukraine.
New US president Donald Trump's repeated promises to improve relations with Russia have fuelled concern in Ukraine that Washington would back off some of the sanctions.
The upsurge of hostilities around Avdiivka coincided with last weekend's phone conversation between Mr Trump and Russian president Vladimir Putin.
Mr Putin on Thursday accused the Ukrainian leadership of ordering the attack in the east to appear the victim and secure US and EU support.
OSCE monitors on Friday visited a water filtration plant near the front line that has been damaged by shelling. The plant is crucial for clean water on both sides.
Mr Hug warned that damage to the water plant in Yanysuvata, which has cut the supply to Avdiivka, could lead to a "potential humanitarian and ecological disaster".
A British photographer was wounded by shards of glass in Avdiivka in shelling on Thursday night, according to the Facebook page of Ukraine's anti-rebel military operation.