Ukrainian forces say that they have ended a combat operation aimed at defending a steel plant in the strategic port city of Mariupol.

Russia's forces repeatedly urged the Ukrainian troops to surrender and leave the besieged Azovstal steel plant, as fighting intensified for control over eastern Ukraine. But, the Ukrainian troops fiercely defended their last stronghold in the city.

The General Staff of Ukraine's Armed Forces issued a statement on Tuesday. It said, "The Mariupol garrison has fulfilled its combat mission." It was referring to the troops at the steel plant. It also said the supreme command had ordered the units to save the lives of the soldiers.

Ukrainian President Volodymyr Zelenskyy released a video message earlier on Monday. He said that an operation aimed at saving the defenders had begun.

Zelenskyy said, "There are severely wounded ones among them...Ukraine needs Ukrainian heroes alive."

Deputy Defence Minister Anna Malyar said 53 heavily wounded soldiers were taken from the steel plant to a hospital in a Russian-controlled town in the Donetsk region. She said another 211 were evacuated to a different Russian-controlled town by way of a humanitarian corridor.

Malyar added that the evacuees could become part of a future prisoner exchange deal with Russia.