Russian forces shelled the entire front line of the Donetsk region in eastern Ukraine on Thursday, Ukrainian officials said, part of what appeared to be the Kremlin's scaled-back ambition to secure only the bulk of lands it has claimed.

The fiercest fighting was near the towns of Bakhmut and Avdiivka, the region's governor Pavlo Kyrylenko said in a TV interview. Artillery slammed into the town of Toretsk southwest of Bakhmut, killing one civilian and damaging 12 buildings, Kyrylenko said.

He said "the entire front line is being shelled" and Russian troops were also trying to advance near Lyman, which was recaptured by Ukrainian forces in November, one of a number of setbacks suffered by Russia since invading its neighbor in February.