Ukraine conflict: Death toll rises ahead of peace talks

At least two people were killed when a Donetsk bus station was shelled

More than 20 people have died in violence in eastern Ukraine as the leaders of Russia, Ukraine, France and Germany prepare for peace talks.

Nineteen Ukrainian soldiers have been killed, many of them in a town which pro-Russian rebels say they have surrounded.

Five people were reported killed by shelling in rebel-held Donetsk.

Negotiators in Belarus are still trying to narrow differences ahead of Wednesday's planned peace summit.

Ukraine and the West accuse Russia of sending troops and arms to support the rebels, but Russia denies this.

The summit in the Belarusian capital Minsk is expected to focus on securing a ceasefire and the withdrawal of heavy weapons, as well as the creation of a demilitarised zone.

Territorial gains

More than 5,400 people have died since the conflict began. Civilian casualties have risen in recent weeks, with 263 civilians killed in populated areas between 31 January and 5 February.

With both sides seeking territorial gains before a potential ceasefire, there are fears that the violence could undermine attempts to secure a long-term deal.

The majority of Ukrainian military casualties were near Debaltseve, a major transport hub where thousands of soldiers are under rebel siege.

Ukraine's president (C) was shown an unexploded rocket that landed deep inside government territory

The separatists say they have cut off the main supply road into the town from the west as they try to capture a tongue-shaped area that cuts into the eastern regions of Donetsk and Luhansk.

While the government wants a demarcation line based on the failed ceasefire agreed on 5 September in Belarus last year, the rebels want a new truce to reflect the gains they have made in recent weeks, the BBC's James Reynolds reports from Donetsk.

At least two people were killed in the city and several more injured when a shell hit a bus station in rebel-controlled Donetsk early on Wednesday. Three more deaths were reported overnight by local authorities.

Responding to the surge in violence, Ukraine's President Petro Poroshenko said Wednesday's summit was one of the final chances to bring about an unconditional ceasefire and withdrawal of heavy weapons.

He was visiting the scene of a rocket attack in the city of Kramatorsk, deep into government-held territory, in which soldiers and civilians were killed.

Volunteer pro-government fighters have also seized territory this week, capturing villages from the rebels outside the government-held of Mariupol.

US President Barack Obama warned President Vladimir Putin late on Tuesday that Russia would face greater costs if it continued its "aggressive actions" in Ukraine.

He urged his Russian counterpart to seize the opportunity of fresh talks to find a peaceful solution to the war that has raged since April last year.

President Obama phoned Mr Putin on the eve of the talks to reiterate US support for Ukraine, just days after he refused to rule out supplying "lethal defensive weapons" to Kiev if diplomacy fails.

Russia, however, has warned the West that sending arms to Ukraine would worsen the crisis.