Ukraine and pro-Russian rebels swapped hundreds of prisoners on Friday as part of a new push for peace that came despite Kiev's decision to cut off key transport links to breakaway Crimea.

The prisoner exchange on a dark and isolated stretch of a road north of the devastated eastern rebel stronghold of Donetsk unfolded as negotiators from both sides held video talks on Skype at reviving stalled negotiations.

Ukraine said on Friday it was suspending all rail and bus services to Russian-occupied Crimea because of security concerns.

Ukrainian and pro-Russian rebel leaders tried on Friday to revive peace talks that stalled after just one round due to stark difference over how to end the eight-month separatist war.

A tense meeting mediated by European and Russian envoys in the Belarussian capital Minsk on Wednesday was due to have been followed by a final one on Friday at which a comprehensive peace accord was signed.

The latest push for peace in Ukraine appeared moribund on Thursday after initial talks failed to agree when the warring sides should meet again to try to end an eight-month pro-Russian revolt.

Negotiations mediated by European and Russian envoys in the Belarussian capital Minsk broke up after more than five hours on Wednesday with the separatists reporting progress on only one of four contentious points.

The big tree with the glimmering holiday lights is up but the festive spirit is missing on Lenin Square in the heart of east Ukraine's rebel stronghold of Donetsk.

Russian authorities' attempts to jail Kremlin critic Alexei Navalny and intimidate his supporters could backfire and trigger new political protests amid the most serious financial crisis of Vladimir Putin's rule.

Thousands pledged to take to the streets after Russian prosecutors this month called for the charismatic 38-year-old leader of the country's beleaguered opposition movement to be sentenced to 10 years in prison for alleged fraud.

Ukrainian and rebel envoys resumed intense talks on Wednesday aimed at ending a pro-Russian uprising that has left the ex-Soviet republic in ruins and upset East-West ties.

A successful round of preliminary negotiations in the Belarussian capital Minsk would pave the way for a second meeting on Friday at which a final agreement is signed.

Russian investigators Wednesday said they had new proof from a witness that a Ukrainian pilot fired a missile on the day of the Malaysia Airlines crash which killed 298 people.

The witness, who was not named, worked at an airfield in the Ukrainian city of Dnipropetrovsk where he claimed to have seen a warplane take off on July 17 with air-to-air missiles and return without them.

Ukraine took a historic step toward NATO on Tuesday in a parliamentary vote that stoked Russia's anger ahead of talks on ending the ex-Soviet state's separatist war.

Lawmakers in the government-controlled chamber overwhelmingly adopted a bill dropping Ukraine's non-aligned status -- a classification given to states such as Switzerland that refuse to join military alliances and thus play no part in wars.

The gruesome murders of foreign journalists by the Islamic State group contributed to 2014 being a particularly deadly year for international correspondents, an annual review by the Committee to Protect Journalists reported Tuesday.

The CPJ study found that an "unusually high proportion" of the 60 journalists who died reporting from the world's trouble-spots in 2014 were international journalists.