At least 19 soldiers and civilians were killed in clashes across east Ukraine as fierce fighting raged Sunday between government forces and pro-Russian rebels following the collapse of ceasefire talks.

Ukraine's military said that 13 soldiers had died and 20 were wounded over the past 24 hours, pushing the military death toll over the past two days to 28.

Peace talks aimed at halting rising bloodshed in eastern Ukraine ended in failure Saturday, with Kiev's envoy saying pro-Russian separatists wrecked a deal by refusing to discuss an immediate ceasefire.

The delayed talks in Minsk were "thwarted" after top rebel leaders stayed away and their negotiators also refused to discuss withdrawing heavy weapons, former Ukrainian president Leonid Kuchma told Interfax Ukraine news agency. 

Three people died and 24 were injured in a bus crash in northern Slovakia early on Saturday, rescuers said.

"Three people died, two are in a critical condition, four suffered serious injuries and 18 had light injuries," emergency service spokesman Andrej Hirjak told Agence France Presse, adding the accident had occurred around 0300 GMT.

Hungary's maverick Prime Minister Viktor Orban has spent the past year straddling the divide between Russia and his European Union counterparts on the crisis in Ukraine.

But he may soon be forced to pick sides.

U.S. Secretary of State John Kerry will visit Ukraine next week amid growing global concern over the intensifying nine-month war in the country's east that has killed more than 5,000 people.

The trip will come as the EU and the U.S. are mulling fresh sanctions against Russia, accused of arming and aiding the pro-Russian separatists in eastern Ukraine.

Two Russian television journalists working for the pro-Kremlin Life News channel have been arrested in Ukraine and will be expelled, Ukraine's security service (SBU) spokesman Markiyan Lubkivskiy said on Friday.

"The SBU arrested two Russian citizens working as journalists for Life News. Their residency permits have been canceled and they will be expelled from our country and barred from returning to Ukraine for three years," Lubkivskiy wrote on his Facebook page.

Truce talks between Ukraine's government and pro-Russian insurgents appeared to collapse Friday after 24 people, mostly civilians, were reported killed in heavy weapons fire in eastern Ukraine, prompting new European criticism of Russia.

Plans for the talks in the Belarussian capital Minsk were announced on Thursday, raising hopes of dialogue amid the collapse of a September truce in a war that has killed at least 5,100 people, according to the United Nations.

Twenty-four people, including 19 civilians, were killed in the past 24 hours in clashes between government forces and pro-Russian rebels in east Ukraine, officials said Friday.

Pro-Kiev officials in the separatist region of Donetsk said dozens of people were also wounded in shelling across the industrial province. The Ukrainian military said 23 soldiers were injured in the fighting, which has claimed at least 5,100 lives over the last nine months.

The United States warned Russia on Thursday that it is mulling fresh sanctions over the fighting in Ukraine and welcomed an EU move to broaden existing measures imposed on Moscow.

State Department spokeswoman Jen Psaki said the agreement by EU foreign ministers to expand existing European sanctions "is just a further sign that the actions of the last several days and weeks are absolutely unacceptable and that there will be new consequences put in place."

The EU agreed Thursday to expand its sanctions against Russia as Ukraine's warring parties announced fresh truce talks to end a surge in fighting between Kiev and Kremlin-backed rebels.

Former Soviet leader Mikhail Gorbachev warned meanwhile that the threat of further sanctions risked turning the new Cold War atmosphere into a globally destabilizing "hot" armed conflict between Moscow and the West.