Ukraine crisis: Russia conditions unacceptable - Poroshenko
Ukrainian President Petro Poroshenko has said Russian conditions in ongoing negotiations in Belarus over the conflict in Ukraine are "unacceptable".
He was speaking to reporters during a break in marathon talks involving Russian President Vladimir Putin.
The four-way meeting, also being attended by the leaders of France and Germany, began late on Wednesday and continued into Thursday morning.
Thousands of people have been killed in the fighting in the east of Ukraine.
German Chancellor Angela Merkel and French President Francois Hollande are leading the peace initiative in Minsk.
After about 14 hours of overnight talks, Mr Poroshenko said there was "no good news yet".
He told reporters that Russia had set "conditions that I consider unacceptable". He declined to elaborate but added that there was "always hope" as talks were continuing.
They were set to focus on securing a ceasefire, withdrawal of heavy weapons and creating a demilitarised zone.
Russia has been accused of arming and reinforcing pro-Russian rebels in eastern Ukraine - a claim it denies.
While the Ukrainian government is seeking a demarcation line based on the failed ceasefire agreed on 5 September in Belarus, the rebels want a new truce to reflect the gains they have made in recent weeks, the BBC's James Reynolds reports from Donetsk.
Meanwhile the International Monetary Fund (IMF) has offered Ukraine a $17.5bn funding package (£10.5bn; 15.5bn euros) to help the country's struggling economy.
Alongside other sources, this would reach $40bn over a four-year period, IMC chief Christine Lagarde said.
At the scene: Lyse Doucet, BBC chief international correspondent
The images tell you an awful lot. The Ukrainian and Russian presidents barely looked at each other when they were forced to shake hands at talks began. At a family photo of the leaders, not a single person was smiling. There was even an image of Vladimir Putin inside the negotiations snapping a pencil in two.
In the end, what it will come down to is what the Ukrainian President, Petro Poroshenko, is willing to accept in terms of a compromise and what Russia is willing to offer.
In broad terms what Ukraine, backed by the West, wants is to restore Ukraine's territorial integrity, including control of the border with Russia. But what the separatists in eastern Ukraine, backed by Russia, want is to remain in charge of the territory that is now under their control.
The best that anyone says can be achieved is a freezing of the conflict.
More than 5,400 people have died since the conflict began, and there has been a dramatic rise in casualties in recent days, with 263 civilians killed in populated areas between 31 January and 5 February.
Russian Foreign Minister Sergei Lavrov cautioned against making an issue of Ukraine's unguarded eastern border with Russia.
"To give away the Russian part of the border also would be to cut them [the rebels] off even from humanitarian help and allow them to be surrounded,'' he said in Moscow.
The US has refused to rule out supplying "lethal defensive weapons" to Ukraine if diplomacy fails, but Russia says that would worsen the crisis.
Rival agendas at Ukraine talks
Ukraine: Restore government authority over breakaway areas, though Donetsk and Luhansk regions could get greater self-rule; disarm rebel forces; withdrawal of Russian troops; restore Kiev's control over Ukraine-Russia border; full prisoner exchange.
Pro-Russian rebels: Separation from rest of Ukraine and recognition of "people's republics" of Donetsk and Luhansk; no disarmament of separatist forces; amnesty for separatist leaders.
Russia: Legal guarantees for rights of Russian-speakers in eastern Ukraine; full autonomy for Donetsk and Luhansk in a federal system - not necessarily independence; no return of Crimea to Ukraine; withdrawal of Ukrainian troops from combat zone.
EU and US: Restore Ukraine's territorial integrity; end Russian intervention in eastern Ukraine - withdrawal of all Russian troops and heavy weapons; effective monitoring of Russia-Ukraine border and demilitarised zone between the combatants; full democracy in Donetsk and Luhansk.
Ukraine's war: The human cost
- At least 5,486 people people killed and 12,972 wounded in eastern Ukraine but true numbers could be much higher
- Fatalities include 298 people on Malaysia Airlines flight MH17 shot down on 17 July
- 5.2 million people estimated to be living in conflict areas
- 978,482 internally displaced people, including 119,832 children
- 600,000 fled to neighbouring countries, of whom more than 400,000 have gone to Russia
Source: Figures from UN report, 6 February
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