Russian President Vladimir Putin told his defense minister in a televised meeting to cancel plans to storm Ukraine's final stronghold in Mariupol and instead block the Azovstal steel plant so "not a fly" can escape.

The big picture: Ukrainian officials earlier called for a "special round of negotiations" in Mariupol without conditions in order to help evacuate civilians from the besieged southeastern port city's steel plant.

• Ukraine's President Volodymyr Zelensky said Wednesday about 1,000 civilians were sheltering at the plant, as Russia's military continued to bombard Mariupol.

What he's saying: "I consider the proposed storming of the industrial zone unnecessary. I order you to cancel it," Putin told Defense Minister Sergei Shoigu at the Kremlin in Moscow, according to a Reuters translation.

• "There is no need to climb into these catacombs and crawl underground through these industrial facilities," he continued. "Block off this industrial area so that a fly cannot pass through."

What to watch: Mykhailo Podolyak, a Ukrainian presidential aide and negotiator, tweeted on Wednesday that he was calling for negotiations "right in Mariupol" to "save our guys, Azov, military, civilians, children, the living and the wounded."

• Ukrainian Deputy Prime Minister Iryna Vereshchuk said in a Telegram post on Thursday morning that "four evacuation buses managed to leave Mariupol yesterday through the humanitarian corridor," spending the night in Berdiansk before heading to Vasylivka, according to a Guardian translation.
• "We are waiting for them in Zaporizhia," but the security situation remained difficult, she added.

State of play: Maksym Zhorin, co-commander of Ukraine's Azov regiment, said in a televised address Thursday that Russian forces "have not stopped shelling areas of Mariupol," CNN reports.

• "There are more than 100,000 people in the city, some of them under rubble, some in basements," Zhorin said, adding many were at the steel plant.
• "There are a lot of children, a lot of women, the elderly. And today, while agreeing on a green corridor, the Russians simply cynically fired on fortifications, on shelters where civilians were," Zhorin added.

Meanwhile, Maj. Serhiy Volyna, commander of Ukraine's 36th Separate Marine Brigade that's defending the plant, has so far resisted Russian calls to surrender and has vowed to fight to the end.

• "We are probably facing our last days, if not hours," he said Wednesday.

Editor's note: This article has been updated with new details throughout.