Russia is dropping bunker-buster bombs on a steel plant in the southeastern Ukrainian city of Mariupol where soldiers and citizens have been hiding, a Ukrainian military commander said, writes businessinsider.com.

Denys Prokopenko, the commander of the Ukrainian National Guard"s Azov Regiment, said on Monday that Russia had started dropping bombs on the Azovstal Iron and Steel Works plant, the Associated Press reported.

Prokopenko said his troops were there alongside civilians.

The plant includes underground tunnels, and Mariupol"s city council said on Telegram on Monday that up to 1,000 citizens were also hiding there.

Bunker busting bombs are designed to hit targets that are deep underground and to penetrate through thick defenses.

Prokopenko said Russian troops were aware that civilians were hiding there, and firing anyway: “Russian occupational forces, and their proxy ... know about the civilians, and they keep willingly firing on the factory”.