KIEV - Ukraine's new Western-backed president agreed on Sunday to dialogue with those separatists not implicated in "murder and torture" as he laid out a peace plan for ending the pro-Russian insurgency threating his ex-Soviet state.
Petro Poroshenko's initiative follows his announcement on Friday of a week-long unilateral ceasefire in the government's 10-week "anti-terrorism" campaign in the industrial east that has claimed more than 375 lives and displaced tens of thousands of people.
The hostilities raged on Saturday despite the oder as federal forces used artillery fire to repel waves of raids by militias who rejected the terms of his pact.
And it also received only a lukewarm endorsement on Saturday from Russian President Vladimir Putin.
The Kremlin chief said he backed Poroshenko's proposal while noting that "any peace initiative not aimed at starting the negotiating process will not be viable or realistic".
The 48-year-old confectionery tycoon - elected on May 25 in snap polls called after month of deadly pro-EU protests toppled Kiev's Kremlin-backed president in February - said that a peaceful settlement was "our plan A".
"But those who are planning to use peaceful negotiations only to buy time and regroup their forces must know that we have a detailed plan B. I am not going to speak of it now because I believe that our peaceful plan will work out," he added in the 12-minute address.
One top separatist leader had earlier said that Poroshenko's efforts were "meaningless" unless they included the complete withdrawal of state troops from the heavily Russified eastern rustbelt and recognition of the independence they proclaim last month.
But Putin took the extra step on Saturday to call on "the conflicting parties to halt all military activities and sit down at the negotiating table" - a comment that implied a degree of criticism for the rebels' continued attacks.
On Sunday Poroshenko opened the door to talks, saying that the "immediate fulfilment of the peaceful plan will open the path to the political dialogue." "I am ready to talk with those who have erred, who mistakenly stood in the position of separatism," he added.
"Except, of course, people who were involved in the acts of terrorism, murder or torture." Poroshenko said parliament would soon draft a bill granting amnesty "to those members of illegal armed formations who did not kill civilians and Ukrainian soldiers." He vowed to enshrine in the constitution locals' right to use the Russian language - one of the east's most pressing concerns - and also offered them broader autonomy, including a greater say in who serves as regional governor, currently appointed by Kiev.
And Poroshenko confirmed plans to establish a 10-kilometre (six-mile) buffer zone along the Russian border to stem the flow of weapons and gunmen from Ukraine's giant neighbour.
Both Kiev and its Western allies are anxious about the presence of new Russian forces along the frontier amid charges of growing flows of heavy weapons crossing into rebel-held parts of the east.
Ukrainian officials have told EU and G7 teams in Kiev that they had evidence of 10 additional tanks and sealed trucks coming over the border close to the eastern city of Lugansk since Thursday.
US State Department spokeswoman Jen Psaki noted that most of the equipment being gathered in southwest Russia was no longer used by its military.
"We believe that Russia may soon provide this equipment to separatist fighters," Psaki said.
Poroshenko also stressed that the ceasefire - due to expire on Friday morning - did not meant that his forces would not defend themselves if attacked.
"All illegal armed formations must understand: the ceasefire we initiated does not mean that Ukrainian soldiers are forbidden to shoot back. Any attempts by militants to attack will be rebuffed. Of course, not verbally."