Russia's president Vladimir Putin has said that the crisis in Ukraine has evolved into a full-scale civil war, blaming the US for backing the overthrow of former president Viktor Yanukovich.

Putin's comments came on Friday, just two days before Ukrainian presidential elections were due to take place.

"The Ukrainian crisis arose because Yanukovich postponed the association agreement with the European Union. This was followed by a coup backed by our American friends and as a result there is chaos and full-scale civil war," he told an economic forum in Russia's St Petersburg.

Putin's remarks came on a day at least eight people were killed in fighting in the village of Karlivka, near the city of Donetsk, Al Jazeera's John Wendle reported from the scene.

Four of the dead appeared to be members of the self-styled Vostok Battalion while one man with a swastika tattoo seemed to have fought for the Donbass Battalion. Both the volunteer groups are known for their pro-Moscow sympathies.

In another development on Friday, Oleksandr Turchynov, Ukraine's interim president, appealed to voters to come out and show their support for a free and democratic Ukraine.

"We will never again stand being denied freedom and independence or seeing our Ukraine being turned into a part of a post-Soviet empire," Turchynov said in a brief nationally televised address.

In the face of pressure from the West, Russia has ordered a withdrawal of all forces deployed to regions near its border with Ukraine.

Anatoly Antonov, Russia's deputy defence minister, told Reuters news agency that the Kremlin would leave "less than nothing behind", withdrawing all of its troops "within a few days".