KIEV - Ukrainian troops and pro-Russian separatists were locked in fierce fighting in the east of Ukraine on Thursday after rebels rejected a call to lay down their arms in line with a peace plan proposed by President Petro Poroshenko, government forces said.
Heavy fighting broke out at around 4 a.m. near the town of Krasny Liman, which itself has been under government control since early this month.
"We issued an ultimatum to the terrorists overnight to surrender their weapons. We guarantee their safety and investigation in line with Ukrainian law ... They refused," said government forces spokesman Vladyslav Seleznyov.
"Now we are trying to narrow the encirclement. They are trying to break out," Seleznyov said.
No details of the fighting were immediately available from the rebels side.
Poroshenko, installed as a president on June 7, is pushing a peace plan to end the separatist rebellion including an offer of a unilateral ceasefire by government forces and amnesty for the separatists as long as they put down their weapons.
Poroshenko was due later on Thursday to meet regional officials from the Donetsk and Luhansk areas of eastern Ukraine to explain his plan.
Separatist rebellions erupted in eastern Ukraine in early April after street protests in Kiev toppled the Moscow-backed leader Viktor Yanukovich and Russia in turn annexed the Crimean peninsula. Eastern rebels have called for union with Russia.
Kiev has accused Russia of fomenting the unrest in the east and of allowing volunteer fighters from Russia to cross into Ukraine to support the rebels. This is denied by Moscow.
The violence has cost the lives of 147 Ukrainian soldiers and wounded 267 up to now, the defense ministry said on Wednesday. But many scores of separatist militia, civilians and members of other military bodies such as the national guard have also been killed.
Ukrainian forces, which lost 49 servicemen on June 14 when separatists brought down a military helicopter in Luhansk region, have been gradually tightening their encirclement of rebel positions.