A group of vigilantes have been hunting and capturing people they consider to be "pro-Russian thugs" in the eastern Ukraine city of Dnepropetrovsk, according to footage released on YouTube.

In the video, the "thugs" are captured, frisked and handed to police by masked Ukrainian men wearing paramilitary uniforms.

The men run after the Russian "thugs" and catch them before accusing them of staging a pro-Russian strike at a police station.

The masked men call the captured pro-Russians "titushki" (hired thugs) with one man having a knife held to his throat and another punched in the face. The men were then dragged to a police station to "check their identities".

The alleged pro-Russians were wearing St. George ribbons, a symbol of the Soviet Union's role in thwarting Nazi Germany.

The video has gone viral in Russia with over 350,000 views and many comments against alleged Ukrainian neo-Nazism or fascism.

Tensions have continued to escalate in eastern Ukraine as Russia mobilises its forces on the Russian border.

Russian troops have seized three military bases in Crimea following President Vladimir Putin's annexation of the Russian-dominated region.

There are now concerns that Putin has set his sights on another area with a prominent Russian-speaking population, Transnistria.

Both Russia and the United States have imposed sanctions on officials from the opposite side with visa bans and asset freezes.

US president Barack Obama has dismissed fears that the Western standoff with Russia over the Ukraine crisis would lead to another Cold War but has warned that if Moscow stays on its course "costs will increase and sanctions will extend".

"This is not another Cold War we're entering into," he said in Brussels. "Russia leads no bloc of nations. The US and Nato do not seek any confrontation with Russia."