A Russian drone struck a Warsaw-bound passenger train from Kiev on Sunday but caused no casualties, Warsaw and Kiev said, as Ukrainian President Volodymyr Zelenskyy said western regions had come under attack.

Ukraine said it was struck just two kilometres (1.2 miles) from the border with NATO member Poland, hitting the locomotive of the passenger train, with Zelenskyy saying Moscow struck it "deliberately".

Poland said another drone struck near a border crossing.

Zelenskyy said Russia had attacked Ukraine's rail and energy facilities as well as "ordinary buildings", including in the west of the country, as Moscow intensifies strikes in the fifth year of the war.

"All necessary services are working near the Polish-Ukrainian border in Volyn, where the Russians deliberately burned a train locomotive and damaged a gas station in a drone strike," Zelenskyy said.

"It is precisely to prevent these strikes from spreading further into Europe that Ukrainian men and women fight every day, give their lives, and do not allow the aggression to expand," Zelenskyy said.

Poland's PKP Intercity rail service said the train was travelling from Kiev to Warsaw with 206 passengers onboard.

Neither country reported casualties and Intercity said the service was delayed by more than six hours but will travel on to Warsaw after border checks were completed.

Poland's interior minister Marcin Kierwinski said one drone struck near the Dorohusk-Yagodyn border crossing, while the other hit the passenger train.

"We are treating these events with the utmost seriousness. The situation is being monitored on an ongoing basis," Kierwinski said.

The strikes came days after US envoys visited both Moscow and Kiev in an effort to revive talks led by Washington on ending Europe's worst conflict since World War II.

At least two civilians were killed by Russian strikes in Ukraine on Sunday.