Ukraine's Interior Minister Arsen Avakov said police have driven pro-Russian separatists out of the city hall in the eastern city of Mariupol.
Avakov said in a Facebook post Thursday that city officials are free to return to work. He gave no details how the building was retaken, but reported no casualties.
The government also said Ukrainian forces repelled an attack by armed separatists on an army base in the town of Artemivsk. One soldier was wounded.
Ukraine says it is relaunching what it calls "anti-terrorist" operations against armed pro-Russians who have taken over government buildings in about a dozen eastern cities. The separatists are demanding the right to vote on whether to split with Ukraine and join Russia.
President Barack Obama, speaking to reporters Thursday in Tokyo, said Russia is not abiding by the Geneva agreement to ease the crisis in Ukraine and he is not hopeful the Russians will cooperate.
He said Russia has chosen not to take the "wise path" and faces stronger sanctions, while, he said, Ukraine has been taking the concrete steps agreed to last week in Geneva. That includes offering amnesty to pro-Russian separatists who leave the buildings peacefully.
Russian Foreign Minister Sergei Lavrov Thursday accused the United States of trying to orchestrate a "color revolution" in Ukraine. He said Washington is using Ukraine as a pawn in a geopolitical game.
Lavrov said the West is acting like winners of the Cold War and do not consider Russia's interests when drawing up European policies.