Inside, the building is mostly empty, with just a handful of rebels in gas masks wandering through the ransacked offices in the four-storey block with Russian separatist flags flying from the roof.

Barricaded behind rows of tyres and barbed wire, the city hall has been the headquarters of the separatist movement in this Black Sea port town since it was seized last month.

Early Wednesday morning, bystanders said, government troops moved in with teargas grenades to clear the building of its mainly unarmed occupiers before briefly hoisting the Ukrainian flag and departing just as quickly when a crowd of several hundred pro-Russians gathered.

For Kostinyuk the reason for the raid is clear– the authorities want to prevent a rebel referendum planned for Sunday that would see people vote on breaking away from Kiev and potentially joining Russia.

“They want to stop us from holding the referendum,” the factory worker, 27, told AFP.

“It would be possible to organise it as we’ve got enough people willing to help but the authorities don’t want to let us.”

Local officials have dismissed the rebel attempts to conduct the referendum with derision and pledged that any vote could never be considered legitimate.

But it was not clear Wednesday if it would go ahead after Russian President Vladimir Putin told the separatists to postpone the vote.

And Ukrainian forces appear to be intent on showing that it cannot go ahead by flexing their muscles with shows of strength like Wednesday’s raid.

But they still face a considerable task to reimpose their authority.

Highlighting the instability, government armoured vehicles were parked at a checkpoint just a few kilometres outside Mariupol and officials said they captured the rebels’ self-proclaimed defence minister after a reported armed attack on a bus carrying military personnel nearby.

– ‘I don’t hate anyone’ –

In front of the city hall — the only building the separatists have controlled in this town of some 500,000 — even the diehards in the crowd of mainly elderly people seemed doubtful about any poll taking place.

“I don’t know if we’ll be able to hold the referendum,” said grey-haired local resident Vitaly.

“Even if we can’t hold it, I am sure that 90 percent of the people here would vote for independence from Kiev.”

Nearby, moustachioed Vitaly Tisov sat on a chair peering at the trashed city hall and trying to work out what was happened.

“I don’t know why the soldiers just came in and left again but I guess those were the orders that they had,” he said.

And would the referendum take place?

“That’s the main question now,” he said shrugging.

Elsewhere in the crowd, vegetable seller Natalya Vaivovskaya said that whatever happens, she just wanted to see her hometown go back to being the tranquil provincial city it used to be.

“They came in to clear out the separatists — but they’re just normal people here,” she said.

“I don’t care about the referendum. All I want is for there to be peace. I love all people and don’t hate anyone– not even Americans,” she said.