Deadly fighting raged in the eastern Ukrainian port city of Mariupol after Ukrainian security forces stormed a separatist-held police station on May 9.
The Interior Ministry said some 20 "terrorists" had been killed in the battle between security forces and pro-Russian supporters.
But regional health officials were later quoted by pro-Kyiv authorities in Donetsk as saying that seven people had been killed and 39 others injured, based on hospital treatment lists.
Interfax quoted separatists as claiming that Ukrainian security forces used armored vehicles to shell the building. The station burned in the clash.
Mariupol is a major industrial and transport hub on Ukraine's southern coast.
Key buildings in the city of half a million people were taken over by separatists in mid-April.
They have traded hands between Ukrainian government forces and separatists multiple times in the last two days.
The fighting on May 9 came as Ukraine held muted Victory Day ceremonies due to official fears public gatherings could spark clashes between pro-Russian activists and government supporters.
But there were informal gatherings to mark the 69th anniversary of the victory over Nazi Germany in cities across the country, including the restive east.
World War II veterans gathered at Donetsk's Victory Monument to lay wreaths and listen respectfully to the Ukrainian national anthem.
In separatist-controlled Luhansk, veterans rallied beneath flags of the self-declared Luhansk People's Republic.
In Odesa, a crowd of some 70 pro-Russian separatists marched to the trade union building to lay wreaths at a makeshift memorial to the dozens of people who were killed in a fire there during clashes with government supporters last week.
Meanwhile, Ukraine's security service (SBU) said on May 9 that foreign "saboteurs" had knocked out state television transmissions for several hours.
Viktoria Syumar, deputy head of the SBU, said underground cables carrying power and signals to the state broadcaster were set on fire.
The Kyiv mayor's office said earlier that the fire had been due to a short circuit.
State television later returned to the air broadcasting a talk show about Victory Day celebrations.
Ukrainian Prime Minister Arseniy Yatsenyuk said on May 8 that he suspected Russian President Vladimir Putin was planning some form of "skirmish" to discredit Kyiv on Victory Day.
Yatsenyuk spoke after pro-Russian separatists in Donetsk and Luhansk said they will go ahead with referendums on self-determination on May 11 despite calls by Putin to postpone them.
Putin's spokesman said the Kremlin needed more information about the rebels' decision.
Putin, meanwhile, was in Sevastopol for his first visit to Crimea since Russia's internationally unrecognized annexation of the peninsula last month. In a speech after reviewing Russian naval forces there, he hailed Crimea and Sevastopol's return "to the fold of the motherland."
With reporting by "The Moscow Times," AFP, Reuters, RT, Interfax, and ITAR-TASS