Kiev, Ukrain: Five more Ukrainian soldiers have been killed in fighting with Russian-backed separatists in the past 24 hours, a military spokesman said on Thursday.

The fresh casualties were announced as separatists continued attacks on Debaltseve, a key rail hub northeast of the big city of Donetsk which government troops are holding despite strong pressure from the rebels.

"Five Ukrainian service personnel were killed and 29 wounded in the past 24 hours," the spokesman, Vladyslav Seleznyov, told Reuters.

Another military official said the rebels made two attempts overnight to storm Ukrainian positions near Debaltseve, but they were repelled.