Ukraine: Ukrainian tanks attack Luhansk
Rebel military leader Igor Strelkov said his forces had beaten off columns of government armour attacking from the south and west.
Germany and Russia have urged direct talks between Kiev and the rebels.
Pro-Russian separatists have been fighting the government in Kiev since declaring independence in Luhansk and the neighbouring region of Donetsk in April, the BBC reports.
Earlier, Russia accused forces loyal to Kiev of shelling across the border, killing one person and wounding two others. Ukrainian officials have denied involvement.