Ukraine will step up efforts to persuade the United States to send weapons, a government source says, after Washington signalled it might be ready to arm troops battling a rebel offensive.

At least 19 civilians and five government troops were killed over the previous 24 hours as fierce clashes raged between pro-Russian separatists and Ukraine’s outgunned forces in the east of the country, insurgent and government officials said on Tuesday.

US Secretary of State John Kerry is jetting into Ukraine on Thursday in a show of support for the country’s pro-Western leadership as hopes grow in Kiev that long-standing demands for the US to supply arms could be met.

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President Barack Obama’s administration had previously ruled out sending weapons to Ukraine’s government but the failure of economic sanctions to force Moscow to halt alleged military support for the separatists has prompted a second look at the option.

While Kerry is not expected to make any announcements during his trip, a Ukrainian diplomatic source said Kiev was hoping to get more “clarity” on its request during the visit and an upcoming meeting between President Petro Poroshenko and US Vice President Joe Biden in Munich.

Washington – fearful of getting into a proxy war with Russia – has so far provided non-lethal assistance to Ukraine, including flak jackets, medical supplies, radios and night-vision goggles.

But a senior US official told AFP Monday that “what’s being discussed is perhaps we should begin providing defensive weapons” to Ukraine.

As the United States weighed up its options, furious fighting remains focused around the battleground town of Debaltseve, a strategic railway hub between the rebel strongholds Donetsk and Lugansk.

Fighting has surged in recent weeks after separatists tore up a tenuous ceasefire deal and pushed into government-held territory.

Elena Gura was having breakfast with her 16-year-old daughter in Donetsk when a shell crashed through her kitchen ceiling.

“We escaped with 300 hrvyna ($A23) and some identity papers,” she told AFP after miraculously escaping her destroyed house.

The United Nations said Tuesday the civilian death toll has risen by 224 in the past three weeks and that the total of those killed in the conflict since April now stands at over 5358 people.

“Any further escalation will prove catastrophic for the 5.2 million people living in the midst of conflict in eastern Ukraine,” warned UN High Commissioner for Human Rights Zeid Ra’ad Al Hussein.

Hopes of defusing the conflict look more distant than ever after the latest attempt at truce talks collapsed in acrimony in the Belarussian capital Minsk over the weekend.

The rebels say they are willing to stop fighting only if Kiev agrees to redraw the demarcation line agreed in a September ceasefire deal to include gains they have made since in recent days.