UP to eight pro-Russian activists were reported killed in eastern Ukraine today and another eight wounded as heavily armed Kiev troops attacked Mariupol's police headquarters.

Government troops used large-calibre weapons in an attempt to retake the occupied building in the port city, setting it on fire.

Crowds had arrived in the city centre to mark Victory Day, but as reports of shooting started coming in, many moved on to show support for a few dozen policemen who had barricaded themselves inside the building, refusing to hand it over to Kiev forces.

But armoured vehicles manned by Kiev troops then opened fire at a group of unarmed civilians, according to an anti-fascist forces’ representative.

The police HQ was taken by opposition forces on Thursday night and holds one of the largest armouries in the city.

Local militias in eastern Ukraine are pressing ahead with plans to hold referendums tomorrow, despite calls from the Kremlin to postpone them.

The vote in the regions of Donetsk and Luhansk has been the subject of intense debate since Mr Putin called for it to be postponed so talks could take place with the Kiev government.

However, many in the east say a referendum is the only way to prevent war against fascist politicians in the capital.

Russian President Vladimir Putin made his first visit to newly-annexed Crimea yesterday, turning up in Sevastopol to attend a celebration marking Soviet victory over the Nazis in World War Two.