Vladimir Putin arrives in Crimea as a part of Victory Day celebrations, while in eastern Ukraine, where Russia is accused of instigating unrest, Ukrainian soldiers kill 20 pro-Russian separatists.
Warning: the below video contains footage some viewers may find distressing
Arsen Avakov, the interim Ukrainian government’s interior minister, said on Facebook that 20 “terrorists” had been killed after they tried to storm a police headquarters in Mariupol.
Mr Avakov said around 60 men armed with automatic weapons made an attempt to “capture the building”. He said there was a fight inside the building, which turned into a “full-scale military confrontation”.
Mr Avakov said “about 20 terrorists” were killed and four were taken prisoner. He added that a “significant amount” of the pro-Russian’s weapons were also seized.
The remaining attackers were reported to have fled into residential areas of the city. One Ukrainian soldier was killed and five were wounded, and the police headquarters was engulfed in flames.
Mr Avakov said it was “time to stop this madness”. “I ask all friends and enemies,” he wrote, “set aside rivalries and interests – the country is at stake.”
It is the latest violence in an escalating situation in eastern Ukraine ahead of a separtist-planned referendum at the weekend. Dozens were killed in violence in Odessa earlier this month, and the Ukrainian military has conducted camapigns in Kramatorsk and Slaviansk.
Read more from Alex Thomson: Bodies and fire on the streets of Mariupol
Meanwhile in Crimea, Russian President Vladimir Putin sailed into the port city of Sevastopol as a part of his country’s Victory Day celebrations (see video, below).
In a move that western governments have called “provocative”, the Russian president arrived in the city with pomp and ceremony – on show through a range of military aircraft and ships.
Mr Putin congratulated the gathered Crimean citizens for their “loyalty”. He said 2014 would be recorded in history as a year when “the nations living here strongly decided to be with Russia”.
“And with that they confirmed their loyalty to the historical truth and the memory of our ancestors,” he said. “There is a lot of work in front of us, but I and you will overcome all difficulties because we are together, and that means we have become even more powerful.”