The Ukrainian government says its forces have regained control of the rebel-held port city of Mariupol.
The government’s offensive in the southeastern city is part of a broader military operation to reclaim territory from pro-Russian separatists in eastern Ukraine.
Writing on Facebook on June 13, Interior Minister Arsen Avakov said government forces raised the national flag over Mariupol’s main administrative building at 10:34 a.m. local time.
There was no immediate comment by the separatists on the announcement.
Five separatists were reported killed and at least two government soldiers wounded in the fighting in Mariupol.
Earlier in the day, Avakov announced that Ukrainian troops had launched a dawn attack on the city.
The rebels, for their part, said they had blown up an armored personnel carrier carrying government soldiers and that "many" had been injured.
Mariupol, the Donetsk region's second-largest city, is located on major roads from the southeastern border with Russia into the rest of Ukraine.
Avakov said government forces also won back control of a 120-kilometer stretch of the border with Russia that had fallen to the rebels.
And Interfax quoted the Ukrainian Defense Ministry as saying more than 40 rebels transporting "significant quantities of firearms" were killed in a fight near the town of Stepanovka in the Donetsk region.
The ministry said 12 vehicles were also destroyed, including two armored personnel carriers, two tanks, and two trucks.
The report cannot be independently confirmed.
Meanwhile, Ukrainian President Petro Poroshenko spoke with Russian President Vladimir Putin on June 12 to protest after Kyiv said three tanks and other military vehicles had crossed the border from Russia into separatist-controlled areas of eastern Ukraine.
During their telephone conversation on June 12, Poroshenko said such action was "unacceptable."
Russia denied sending in tanks.
Ukraine's interior minister said part of the column had been destroyed on June 12.
During a government meeting in Kyiv, Avakov said two tanks had been attacked after moving in the direction of the rebel-controlled city of Horlivka.
Reuters correspondents reported spotting two tanks in the eastern town of Snizhnye.
The agency said it was unclear whether the tanks had rolled in from Russia or were from a Ukrainian military stockpile.
In Washington, U.S. State Department spokeswoman Jen Psaki said if the military incursion was confirmed, it would be a "serious and disturbing escalation of the crisis in eastern Ukraine."
WATCH: On June 12, an explosion shook the center of Donetsk, where pro-Russian rebels have taken over a regional administration building.
Late on June 12, an explosion shook the center of the eastern city of Donetsk, where the rebels have taken over a regional administration building.
An AP reporter nearby heard the explosion and arrived to see a van in flames in front of the building. He saw three injured people being taken away.
The breakaway "Donetsk People's Republic" said on its Twitter feed that the van was used by one of the group's leaders, Denis Pushilin, but said he was not in the vehicle.
The same tweet said four people were injured and one was in grave condition.
Meanwhile, Russia has submitted a draft resolution to the UN Security Council on the crisis in Ukraine.
According to Russian UN Ambassador Vitaly Churkin, the resolution calls for an end to the violence and implementation of a peace road map authored by the Organization for Security and Cooperation in Europe (OSCE).
Earlier, Russian Foreign Minister Sergei Lavrov said Moscow was getting "increasingly" concerned by the lack of "any progress whatsoever" in stopping the violence in eastern Ukraine, where government troops are battling pro-Russian separatists who control several cities.
The OSCE's secretary-general on June 12 visited a camp in Russia for refugees from eastern Ukraine and called for the fighting to end.
According to the Interfax news agency, Lamberto Zannier said that the conflict in the east "is craziness which must be stopped."
Russia says some 30,000 people have fled the fighting.
Poroshenko this week called for establishing safe-passage corridors for civilians who want to escape the violence, but there have been no visible steps toward creating them.
With reporting by AP and Reuters