Vehicles carrying refugees from the Luhansk area of Eastern Ukraine were hit by rockets and mortar, killing scores of people.
Ukraine has blamed pro-Russian rebels but they have denied carrying out the attack, near the village of Novosvitlivka.
Another military spokesman said that people had been burned alive inside their vehicles but a spokesman for the rebel self-proclaimed “Donetsk People’s Republic”, Andrei Purgin, denied that rebel forces had attacked the convoy.
Ukrainian forces have moved into the outskirts of rebel-held Luhansk where basic supplies are running out.
There has been sustained artillery shelling of the city of Luhansk, where civilians are suffering chronic shortages of water, food and electricity.
Hundreds of civilians are fleeing the city every day as Ukrainian forces edge into Luhansk.
