Heavy fighting resumes in eastern Ukraine

Heavy shelling was reported in the city of Donetsk on Sunday as Ukrainian authorities claimed to have retaken most of the strategically significant airport from pro-Russia separatist forces.

Military spokesman Andriy Lysenko said in a televised briefing that the army had retaken the airport after having lost parts of it to separatists in recent weeks, but it was difficult to independently verify accounts about the now-ruined facility as journalists are not able to approach it.

"The decision was taken for a mass operation… We succeeded in almost completely clearing the territory of the airport," Lysenko said.

Residents of Donetsk reported a steep escalation in fighting, with ongoing shelling including near the city center.

Among the dozens of reported injuries and fatalities among fighters and civilians were two children, who were killed when a shell struck a house in the town of Vuhlehirsk, some 60 kilometers (40 miles) northeast of Donetsk. They were aged 7 and 16, according to news agency reports.

The Reuters news agency, citing Russian agency sources, quotes Kremlin spokesman Dmitry Peskov as saying Moscow was concerned by Sunday's "escalation."

"This state of affairs in no way contributes to the implementation of the Minsk agreements and the future search for a resolution," the Interfax agency quoted him as saying.

Separatists have accused Kyiv of escalating the conflict, with one of their leaders, Alexander Zakharchenko, quoted by Reuters citing Interfax as blaming the shelling around Donetsk on the Ukrainian army.

"We're talking about Kyiv trying to unleash war again," he said, according to Interfax.

A 12-point ceasefire agreed in September in the Belarusian capital, Minsk, and another accord agreed in December have been repeatedly violated by both sides.

'Je suis Volnovakha'

In Kyiv, thousands of people gathered in the city's Independence Square on Sunday for a march to commemorate the 13 civilians who were killed on Tuesday when a commuter bus at a government checkpoint near the eastern town of Volnovakha was hit, likely by shell fire. Ukrainian army forces have blamed the separatists, who have denied responsibility.

Ukrainian President Petro Poroshenko addressed those at the rally.

"We will not give away one scrap of Ukrainian land. We will get back the Donbass ... and show that a very important aspect of our victory is our unity," he said.

Stalled peace talks

The intensifying violence comes as negotiations aimed at peace talks between the warring sides have stalled, with a so-called contact group consisting of representatives from Russia, Ukraine, separatist leaders and the Organization for Security and Cooperation in Europe (OSCE) postponing talks which had been planned for last week. Proposed talks in Kazakhstan between Russian, Ukrainian, French and German leaders are also on ice.

Ukrainian and Western leaders say Russia is supporting and arming the separatist movement in eastern Ukraine, something Moscow has long denied. Russia is struggling with the consequences of economic sanctions imposed by many Western nations as a result of the conflict.

The World Health Organization says more than 4,800 people have been killed in the eastern Ukraine conflict since it broke out in April 2014.

se/gsw (Reuters, AFP, AP)