A senior Ukrainian security source told AFP on Friday that Russia had increased attacks on railway infrastructure with the aim of disrupting movement of military cargo that includes Western aid.
Russian forces have firepower and manpower advantages over Ukrainian forces across the front line and Kyiv has warned that fighting will be especially difficult over the coming weeks.
The uptick in deadly attacks is intended to destroy train facilities and "paralyze deliveries and movement of military cargo" ahead of a planned Russian offensive, the source said.
"These are standard steps ahead of an offensive," they added.
Regional officials and Ukrainian railway operator Ukrzaliznytsia have reported an uptick in deadly strikes on railway facilities.
Three railway employees were killed and four more were wounded, the company said, during a Russian missile attack on the eastern Donetsk region.
Ten civilians were also wounded on Thursday when Russian forces attacked railway facilities in Balakliya the Kharkiv region.
"We see strikes related to railway logistics, and they hit mostly civilian facilities," Oleksandr Pertsovsky, the head of passenger transportation at Ukrzaliznytsia, told AFP.
The Russian Defense Ministry said Friday its forces had hit "Western weapons and military equipment" being transported by railway one day earlier in the Donetsk region, and also targeted railway facilities in the Kharkiv region.
