Captured Ukrainian troops from Mariupol were barely fed and woken up to the Russian National Anthem each morning

• Thousands of Ukrainian troops who defended Mariupol were captured by Russian forces.
• In captivity, they endured abuse and were forced to listen to Russia's national anthem, the New York Times reported.

Ukrainian troops who defended besieged Mariupol's Azovstal steel plant were barely fed and faced abuse in Russian captivity, the New York Times reported on Sunday, citing interviews with soldiers who were captured and later released, civilians, top military officials, and negotiators.

Around 2,500 soldiers who fought at Azovstal were taken to a Russian prison in the Moscow-backed Donetsk People's Republic after surrendering in mid-May, the report said.

While in captivity, the report said, soldiers were barely fed enough to stay alive. The soldiers were also interrogated, locked in confined spaces, and woken up every morning at 6 a.m. to the sound of Russia's national anthem on a loudspeaker, The Times reported.

Ukraine managed to secure the release of nearly 100 Azovstal defenders — many of whom were seriously injured — in a late-June prisoner swap with Russia.

But the families of other soldiers in captivity have no clue if their loved ones will ever return, the Associated Press reported on Friday.

Azovstal's sprawling steel network became Ukraine's last stand in Mariupol, where thousands of soldiers and civilians spent weeks holed up inside the plant.

The steadfast resistance of Ukrainian troops — who, for so long, refused to surrender — managed to bog down Russian forces hoping to declare a swift victory in Mariupol.

The fall of Mariupol in mid-May eventually came after a months-long devastating Russian siege on Ukraine's strategic southern port city that left much of it in ruins. The constant bombardment targeted civilian areas like hospitals and schools, and officials said thousands of civilians were killed.

Mariupol city council accused Russia of wanting to control Mariupol so it could develop a land bridge between the occupied Crimean peninsula and eastern Ukraine's Donbas region.

Moscow-backed separatists have said they plan to tear down Azovstal, which would deny Russia the opportunity to produce steel there.