(Reuters) - A blast hit a crowded market in the southeastern Ukrainian city of Melitopol on Thursday, Ukrainian and Russian-installed officials said, on the eve of referendums that could see four regions effectively annexed by Russia.
Melitopol was one of the first cities to fall into Russian hands after Moscow launched a full-scale invasion of Ukraine in February. It is in the Zaporizhzhia region, one of the four where a referendum will be held on joining Russia.
Ukrainian and Russian-installed officials traded blame for the explosion.
Melitopol's exiled mayor Ivan Fedorov said the attack had been deliberately staged by the occupying Russian forces in order to accuse Ukraine of terrorism.
Fedorov said it had killed three soldiers, while the number of civilian casualties was not clear. Reuters could not independently verify the claim.
Vladimir Rogov, a member of the Russian-installed local administration, said the attack had been carried out by Ukrainian special services to intimidate civilians ahead of the referendums.
In an apparently coordinated move, pro-Russian regional leaders on Tuesday announced referendums for Sept. 23-27 in Luhansk, Donetsk, Kherson and Zaporizhzhia provinces, representing around 15% of Ukrainian territory.
Ukraine and its allies have denounced the planned referendums as a "sham" lacking any legitimacy. Fighting is continuing in all four regions.
(Reporting by Max Hunder; writing by Matthias Williams; Editing by Gareth Jones)