Video provided by Radio Free Europe/Radio Liberty (RFE/RL) purports to show rebel forces firing Grad multiple rocket launchers from the town of Vuhlehirsk in the Donetsk region of Ukraine on Sunday (8 February).
The town, with around 9,000 people before the war, has been one of the main targets of the rebel advance, sitting in a pocket of government-held territory surrounded on three sides by rebel territory and straddling road and rail routes linking major rebel strongholds.
It appeared to be under rebel control completely last week with no sign of areas controlled by Ukrainian troops, when Reuters journalists visited the town.
Fighting in a war which has already killed more than 5,000 people has reached an intensity unseen since before a ceasefire in September.
An attempt to revive peace talks is scheduled to take place on Wednesday in Minsk.