Ukraine's military said on Tuesday it was working to evacuate all remaining troops from their last stronghold in the besieged port of Mariupol, ceding control of the city to Russia after months of bombardment.

The evacuation likely marked the end of the longest and bloodiest battle of the Ukraine war and a significant defeat for Ukraine. Mariupol is now in ruins after a Russian siege that Ukraine says killed tens of thousands of people in the city.

With the rest of Mariupol firmly in Russian hands, hundreds of Ukrainian troops and civilians had holed up beneath the city's Azovstal steelworks. Civilians inside were evacuated in recent weeks, and more than 260 troops, some of them wounded, left the plant for Russian-controlled areas late on Monday.

"The 'Mariupol' garrison has...