Officials in rebellion-wracked eastern Ukraine say at least eight civilians have been killed by fighting and shelling in two cities held by separatist militants.

Authorities in Luhansk said Monday that five people were killed and 15 injured by overnight artillery strikes. Three were killed in Donetsk as a result of clashes, the city's government said.

Territory between the cities has seen intensified fighting as government troops try to gain control over the area where a Malaysia Airlines plane was downed earlier this month.

Both sides in the conflict have traded accusations over the mounting civilian death toll.

Rebels accuse government troops of deploying artillery against residential areas. Authorities deny that charge, but also complain of insurgents using apartment blocks as firing positions.