Arsen Avakov said that four government troops were wounded as forces retook buildings occupied by the rebels in the center of the city and that troops destroyed a light armored vehicle used by the separatists. An AP reporter saw a bullet-riddled armored vehicle and truck in front of a building in Mariupol.
The renewed fighting came as rebel leaders confirmed they have three tanks. Ukrainian officials have said the tanks crossed from the Russian side of the porous border and were attacked by Ukrainian troops, but there has been no independent confirmation the tanks came from Russia.
Rebel leader Denis Pushilin told Russian state television the separatists, who call themselves the Donetsk People's Republic, have the tanks, but that it was "improper to ask" where they had gotten them.
Ukraine and the West have accused Moscow of fomenting the unrest in the east, but Russia has denied sending troops or weapons to Ukraine.
Ukrainian President Petro Poroshenko, who took office less than a week ago, on Thursday rallied support for his plan to end fighting in phone calls with Russian President Vladimir Putin and German Chancellor Angela Merkel.
Poroshenko told Merkel he is willing to negotiate, but not with what he calls terrorists, and could offer amnesty to those who don't have "blood on their hands."
According to his spokesman, Svyatoslav Tsegolko, he told Putin it was "unacceptable" that tanks had crossed the border, while a Kremlin statement said Poroshenko told Putin about his plan for resolving the crisis.
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