Ahead of the make or break summit in the Belarusian capital on Wednesday, Ukrainian President Petro Poroshenko said he, French President Francois Hollande and German Chancellor Angela Merkel would speak "with one voice" to Russian President Vladimir Putin, who they accuse of backing the rebellion.

"Either the situation goes down the road of de-escalation, ceasefire... or the situation goes out of control," Poroshenko said after being greeted by Belarusian President Alexander Lukashenko on Wednesday.

EU foreign policy chief Federica Mogherini said the talks between Ukraine, Germany, France and Russia would be a "turning point for good or bad."

Although details of a possible peace deal have not been released, expected sticking points at the talks include drawing a line of division, withdrawing Russian troops and equipment from eastern Ukraine, securing the Ukraine-Russian border and giving the rebels more autonomy.

As the quartet of political leaders arrived in Belarus on Wednesday in a bid to prevent the conflict widening, Ukrainian forces continued to battle against pro-Russian reels for territory.

It was one of the bloodiest days in 10 months of conflict in eastern Ukraine, with shelling killing at least five people in the rebel-held city of Donetsk on Wednesday. According to the defense ministry in Kyiv, some nine soldiers were also killed and 79 other injured on Tuesday.

'Glimmer of hope'

Poroshenko was reported as saying on Wednesday that the conflict could go "out of control" if there were no ceasefire.

Earlier, the Ukrainian leader said he would not rule out introducing martial law throughout Ukraine if diplomacy failed to produce results.

Under martial law, the highest-ranking military officer effectively temporarily takes over as the head of government should civilian authorities fail to function.

Martial law would, however, also affect foreign investment in Ukraine, including a key loan from the International Monetary Fund. Ukraine and the IMF have been in talks over a bailout that could grow to $40 billion (35.4 billion euros).

US President Barack Obama has also warned that he may start delivering arms to Ukraine if Wednesday's summit fails to find a solution to the crisis.

A spokesman for German Chancellor Angela Merkel was marginally more optimistic saying that the meeting in Minsk offered a "glimmer of hope" but nothing more, and that it was not clear "whether a result can be achieved."

One year of bloody conflict

The West and Kyiv have accused Moscow of sending troops as well as sophisticated weapons across the border to bolster separatists in Ukraine, despite the Kremlin's continued denial of playing any direct role in the ongoing conflict.

According to the United Nations, almost 5,400 people have been killed in the conflict in the Donbass region of Ukraine since the annexation of Crimea by Russia in March last year. The number of casualties has increased dramatically in recent days, with 263 civilians killed in populated areas between January 31 and February 5 alone.

ksb/rc (Reuters, AFP, AP, dpa)