By Matt Robinson
MARIUPOL, Ukraine, May 7 (Reuters) - Ukrainian forces seized the rebel-held city hall in the eastern port city of Mariupol overnight, driving out pro-Russian activists, then withdrew, making no attempt to hold onto the building, witnesses said on Wednesday.
Ukraine's Channel 5 television said earlier the Ukrainian National Guard had seized the administrative centre in Mariupol, a mainly Russian-speaking city of half a million and key component in the self-declared breakaway People's Republic of Donetsk that will hold a referendum on secession this weekend.
But witnesses said the soldiers left after smashing furniture and office equipment. The smell of tear gas hung in the air inside the building which was largely empty in the morning, except for activists in gas masks clearing debris.
"They sent them from Lviv," one witness who said he was present told Reuters, referring to the western city that is a stronghold of the Ukrainian language and culture. "There was no shooting. They just told us they wanted us out and that's it."
In the morning, pro-Russian activists were rebuilding barricades outside the building where separatist flags flew and patriotic songs blared out from loudspeakers.
It was at least the second such short-lived change of hands - pro-Kiev militants mounted an overnight raid on April 24, forcing pro-Moscow activists out, but only for the day.
"They don't want us to hold our referendum, but it's our right. That's democracy," one man named Alexander said at Mariupol town hall on Wednesday. "If this keeps going we won't even settle for federalisation," he added, referring to a proposal for regional autonomy within a federal Ukraine.
"We could have negotiated but they won't even talk."
Late on Tuesday, pro-Russian militants in Mariupol told Russian media that at least one checkpoint they had set up on the edge of the city was attacked. One told Itar-Tass news agency that one person was killed in the raid, but there was no confirmation of that. Local media in the city published pictures of barricades of buses and burning tyres on Tuesday evening.
Kiev has declared Sunday's activist-run referendum in the regions of Donetsk and Luhansk illegal, and fears it is but a first step to Moscow annexing the regions as it did Ukraine's Crimea peninsula two months ago.
Russia denies any such ambition but reserves the right to send in troops if it deems Russian-speaking Ukrainians are in danger from what it calls Ukrainian extremists and fascists. (Reporting by Matt Robinson; Writing by Ralph Boulton; Editing by Alastair Macdonald)