President Volodymyr Zelenskyy said he had ordered Ukrainian military leaders to respond to a growing spate of Russian attacks targeting the country's logistics routes, specifically railway infrastructure.

His comments come after Russian forces stepped up their attacks on train facilities, including one last week that left five people dead in a railway car in the eastern Kharkiv region.

Ukraine has managed to keep its nationwide rail network running despite almost four years of war. Russian forces have prioritised the capture of train hubs such as Kupiansk and Pokrovsk in eastern Ukraine.

"The Russian army remains focused on terror against our logistics, primarily railway infrastructure," Zelenskyy said in a post on social media on Monday.

"In particular, there were strikes in the Dnipro region and in Zaporizhzhia, specifically targeting railway facilities," he added.

State railway operator Ukrzaliznytsia warned earlier on Monday that several of its routes in eastern Ukraine were becoming increasingly "high risk," urging passengers to instead use buses.

In the eastern Sumy region, Ukrzaliznytsia said some of its services would monitor for drone threats and stop near bomb shelters if they emerge.