Ukrainian government troops and Russian-backed separatist forces in the Luhansk region have agreed on a new ceasefire, international monitors said.
The Organisation for Security and Co-operation in Europe (OSCE) said that under the agreement, hostilities are to cease today along the line of contact between the warring sides.
It was agreed at negotiations that took place on Saturday that heavy weapons will start being withdrawn from the front at the weekend, the OSCE said.
Igor Plotnitsky, the head of the rebel movement in Luhansk, confirmed the ceasefire deal in remarks to Russia's Interfax news agency, but said no definitive agreement had been reached on the breadth of the demilitarised zone.
He told Interfax the distance could range between 10 and 13 miles (15 and 20km).
Ceasefire deals have been reached before in eastern Ukraine, only to be swiftly violated. A broad truce was agreed upon in early September after all-party talks in Belarus, but hundreds have been killed since then amid daily violations.
Yesterday, a deal was reached to end fighting over the airport in the capital of the Donetsk region, but rocket barrages continued for hours in that area all the same.
There are concerns that any efforts to impose a ceasefire in the Luhansk region could be derailed by infighting among separatist forces.
Although rebel areas are nominally under the control of the self-styled Luhansk People's Republic, much of the territory is in fact presided over by Russian Cossacks, who have frequently demonstratively rejected Plotnitsky's authority.
There have been multiple unconfirmed media reports in recent days of fatal clashes between fighters of the Luhansk People's Republic and Cossack units.
The OSCE said, however, that the Luhansk People's Republic insists it is in control of all Cossack units.