Reports from Mariupol say on Thursday, black uniformed Ukrainian troops stormed the city council building.
Mariupol was taken over by pro-Russia protesters two days ago.
While the city is back under the control of Ukrainian government forces, tensions still continue.
There are no signs of unrest easing in Ukraine’s eastern regions where government forces and pro-Russia protesters have been clashing over the last few weeks.
Pro- Russia protesters call for a referendum similar to Crimea’s March vote that allowed the region to rejoin Russia.
Meanwhile, pro-Russia protesters in Ukraine have said they will go ahead with the upcoming independence referendum, despites Putin’s request for delaying the vote.
The decision comes just one day after Russia’s President Vladimir Putin called for the vote which is scheduled for May 11, to be delayed in order to create better conditions for talks.
On the same day, Putin announced that Moscow has pulled its troops from Ukraine’s border, saying, “We’re always being told that our forces on the Ukrainian border are a concern. We have withdrawn them.”
Ukraine’s acting government re-launched its military operation on April 23 in the eastern and southern regions in a bid to root out the pro-Russia demonstrations.
Nearly 90 people were killed during the Kiev government’s military operations around the flashpoint city Slavyansk and the southern port city of Odessa last week.