Ukraine's interior ministry has said five pro-Russian militants were killed in a raid in the eastern town of Slovyansk. Russian President Putin has said Kyiv's military operations in the east will "have consequences."
Clashes broke out between government forces and pro-Russian separatists in eastern Ukraine on Thursday with the interior ministry in Kyiv saying its forces had killed "up to five" militants.
According to a ministry statement, during an "anti-terrorist operation" its forces removed three checkpoints manned by armed groups at entrances to the eastern town of Slovyansk. "During the armed clash up to five terrorists were eliminated," the statement said.
Earlier on Thursday, Ukrainian Interior Minister Arsen Avakov wrote on Facebook that police cleared the city hall in Mariupol and that it "has been freed to resume work." Separatist forces confirmed the loss of the city hall.
Clashes were also reported by the defense ministry in the eastern town of Artemivsk, 40 km (25 miles) southeast of Slovyansk, where authorities repelled an attack on an army base.
The defense ministry said in a statement that nearly 100 separatists "opened fire with automatic weapons, machine guns and used grenades" in the attack on the military base.
Ukrainian government forces on Tuesday re-launched a military operation to oust pro-Russian protesters and masked gunmen who have been occupying government buildings across eastern Ukraine for nearly two weeks.
Russia criticizes US, EU roles
Russian President Vladimir Putin said Thursday that the deployment of military in east Ukraine by the authorities in Kyiv was a crime against its own people that will "have consequences."
"If Kyiv really began to use the army against the country's population... that is a very serious crime against its own people," Putin was quoted as saying by Russian news agencies.
"That is simply a punitive measure that will without question have consequences... including for our inter-governmental relations," he said. However, he did not specify the nature of consequences.
Meanwhile, Russian Foreign Minister Sergey Lavrov accused the United States and the European Union of being behind the protests that eventually ousted Ukraine's pro-Kremlin president Viktor Yanukovych in February.
"In Ukraine the United States and the European Union tried to stage - let's call things what they are - another 'color revolution', an operation to unconstitutionally change regime," the Interfax news agency quoted Lavrov as saying at a university in Moscow.
Lavrov accused Washington and Brussels of trying to sully Moscow's reputation even before the Ukrainian crisis broke out.
"It is enough to recall the hysterical anti-Russian propaganda which seized the United States and Europe long before the Ukrainian events, their desire to besmirch the Olympic Games in Sochi through every means possible," he said.
The unusually blunt speech follows a week of comments by Lavrov criticizing Western involvement in the Ukraine crisis.
On Wednesday Lavrov said Moscow will respond if its interests are attacked in Ukraine and reiterated his belief that Kyiv had failed to hold up any of its obligations under the agreement reached in Geneva last week aimed at de-escalating the crisis.
hc/dr (Reuters, AFP, AP)