Ukraine crisis: Leaders plan new Minsk peace talks
The leaders of Russia, Ukraine, Germany and France aim to meet in Belarus's capital Minsk on Wednesday to discuss a peace plan for eastern Ukraine.
It comes after leaders of the four countries discussed the ongoing conflict by telephone on Sunday.
More than 5,300 people have been killed by fighting between Ukrainian forces and pro-Russia rebels since April 2014.
Western countries accuse Russia of arming the rebels and sending troops to Ukraine - claims Russia denies.
German Chancellor Angela Merkel and French President Francois Hollande have been leading efforts to establish a new peace plan.
Analysis: Jonathan Marcus, BBC diplomatic correspondent, Munich
The pace of diplomatic activity to reach a deal to resolve the Ukraine crisis has been dramatically accelerating. With German Chancellor Angela Merkel in the driving seat and French President Francois Holland as her co-pilot, the push is on for a deal.
However, while few details have been provided, this is not a substantially new peace plan.
When I spoke to UK Foreign Secretary Philip Hammond on Saturday, he was reluctant to even go so far as labelling it as "Minsk Plus". A deal is still an aspiration rather than an approaching reality.
The level of frustration many Western countries feel against Russia's policies has been palpable - Mr Hammond for example branded President Vladimir Putin as "some kind of 20th-Century tyrant".
The heady optimism surrounding last year's deal evaporated quickly. This year people are much, much more cautious.
The detailed proposals of the peace plan have not been released, but the plan is thought to include a demilitarised zone of 50-70km (31-44 miles) around the current front line.
Mrs Merkel, Mr Hollande, Ukrainian President Petro Poroshenko and Russian President Vladimir Putin held an "extensive" telephone conference on Sunday, German government spokesman Steffen Seibert said in a statement.
The four parties discussed "a package of measures" to try to reach "a comprehensive settlement of the conflict in eastern Ukraine", Mr Seibert said, adding that the leaders aimed to meet on Wednesday.
Russian Foreign Minister Sergei Lavrov said he expected the meeting in Minsk to produce "important decisions".
However, Mr Putin said the planned meeting would only take place "if by that time we manage to agree on a number of points".
Signatories of a previous ceasefire deal - Ukraine, Russia, rebel representatives and the Organization for Security and Co-operation in Europe (OSCE) - would also meet in Minsk on Wednesday, Mr Seibert said.
That deal, which was signed in Minsk last September, failed to end the fighting and the rebels have since seized more ground.
What was the Minsk agreement?
- A ceasefire signed by Ukraine and pro-Russian separatist rebels on 5 September 2014 in Minsk, Belarus
- They agreed to 12 points including pulling back heavy guns by at least 15km (9 miles), releasing prisoners, allowing access to international observers, and setting up a buffer zone on the Russia-Ukraine border. Foreign mercenaries were to withdraw and Donetsk and Luhansk would get wider self-rule
- But military clashes never entirely stopped. Each side accused the other of violating the deal and violence later flared the length of the ceasefire line
- Rebels also held their own local elections in November 2014, in defiance of Kiev. The government responded by saying it would scrap partial autonomy for Donetsk and Luhansk.
Mr Poroshenko said that he hoped the new Minsk talks would lead to a "swift and unconditional" ceasefire by both sides.
The latest push for a peace deal is thought to be spurred by news that the US is considering sending defensive weapons to Ukraine. The move is opposed by many European leaders.
Speaking on Sunday, US state department spokeswoman Jen Psaki said the US remained concerned about fierce fighting reported in the cities of Debaltseve and Mariupol in Ukraine's east.
"We call on all parties to refrain from actions that undercut the current diplomacy," she added.
More than a million Ukrainians have fled their homes since April 2014, when the rebels seized a big swathe of the Luhansk and Donetsk regions following Russia's annexation of Crimea.
Much of the recent fighting has been focused on the strategic town of Debaltseve. The Ukrainian military said on Sunday that rebels had made "numerous attempts" to storm government positions in the area over the past 24 hours, having subjected them to "massive shelling".
It said rebels had sustained heavy losses, though the claim could not be verified. The past day of fighting also claimed the lives of 12 Ukrainian soldiers and 12 civilians, according to Ukrainian and rebel sources.
Ukraine's war: The human cost
- 5,358 people killed and 12,235 wounded in eastern Ukraine
- Fatalities include 298 people on board flight MH17 shot down on 17 July
- 224 civilians killed in three-week period leading up to 1 February
- 5.2 million people estimated to be living in conflict areas
- 921,640 internally displaced people within Ukraine, including 136,216 children
- 600,000 fled to neighbouring countries of whom more than 400,000 have gone to Russia
Source: Figures from UN High Commissioner for Human Rights 3 February, and UN report, 21 January