Kiev (AFP) - Ukraine and pro-Russian insurgents have reached a vital "New Year" truce agreement that will go into effect at midnight Tuesday in the hope of finally ending clashes in the war-scarred ex-Soviet state.

The announcement suggests that the warring sides were more ready than ever to put aside their guns while they negotiate the formal status of the separatist east and other contentious issues.

Yet it also underscores how Western efforts to end one of Europe's deadliest conflicts since the Balkans wars of the 1990s had resolutely failed.

Kiev's pro-Western leaders and the insurgents are fighting over an industrial region the approximate size of Wales that is home to about 3.5 million people and the centre of the splintered nation's coal and steel wealth.

An adviser to Ukrainian President Petro Poroshenko's peace negotiator said the new deal had been agreed in the Belarussian capital Minsk during the latest round of periodic talks.

"We have an agreement about a complete and unconditional ceasefire that will begin at 00.00 hours on the night of December 22-23," Darka Olifer wrote on her Facebook page.

"This initiative is especially needed so that civilians who live in (the separatist east) can spend Christmas and the New Year holidays in peace."

An envoy from the predominantly rebel-run Lugansk province said the new agreement was necessary because of "repeated violations by Kiev" of a loosely-enforced existing truce.

And the head envoy from Organization for Security and Co-operation in Europe (OSCE) that is helping broker an end to the 20-month war said the sides had also agreed to limit their troop and tank movements along the 500-kilometre (300-mile) front.

"We express our expectations and hope that the people of eastern Ukraine can enjoy their New Year and Christmas days in peace and keep these conditions in the future," Russia's RIA Novosti news agency quoted Martin Sajdik as saying in Minsk.

"We have agreed that the sides will refrain from conducting any military manoeuvres, and also reduce to a minimum any movement of forces," the OSCE negotiator added.

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- Past truce failures -

The warring sides had reached a September 1 truce agreement that significantly calmed deadly exchanges of artillery and missile fire along a 30-kilometre-wide (19-mile-wide) buffer zone separating rebel-run territory from the rest of Ukraine.

Yet a new upsurge in violence that began last week has put the September deal under threat.

Kiev on Tuesday reported 30 truce breaches by the insurgents along the front line.

The United Nations estimates that more than 9,000 people -- most of them civilians -- have died since the rebel revolt began in April 2014.

Kiev also claims that the estimated 40,000 rebel fighters are being backed up by about 8,000 Russian troops.

Russian President Vladimir Putin has repeatedly denied playing any direct role in the conflict.

But he admitted for the first time last week that there were "people (in Ukraine) who work on resolving various issues there, including in the military sphere."