Mr. Putin ordered not to attack the Azovstal Steel Plant in the city of Mariupol.

"Mariupol has been liberated," Russian Defense Minister Sergei Shoigu reported to President Vladimir Putin today in a televised meeting, referring to the strategic port city of Mariupol in southern Ukraine. "The remaining nationalist groups are hiding in the Azovstal Plant."

According to the Russian Defense Minister, it will take 3-4 days to complete control of this plant. "During the liberation of the city, more than 4,000 militants were killed, 1,478 surrendered. The remaining group, about 2,000 people, are surrounded in the Azovstal Plant," Mr. Shoigu said.

"Completing the military task of liberating Mariupol is a great achievement, I congratulate everyone," President Putin said, but ordered no attack on the Azovstal stronghold. He said it was "unwise" to send troops into the giant industrial complex with many basements, and instead ordered Russian forces to tightly surround the plant.

"There is no need to climb into these basements and go underground through industrial facilities. Surround the industrial zone so tightly that not even a fly can fly through," President Putin said.

Smoke rises from the Azovstal Iron and Steel Plant area on April 18 after being shelled by Russian forces. Photo: Reuters.

The Russian President also asked the Defense Minister to continue calling on the Ukrainian forces entrenched inside the factory to lay down their weapons and surrender and treat them humanely, in accordance with international conventions.

Minister Shoigu added that more than 140,000 civilians had been evacuated from Mariupol and hostages taken by "radical groups", including sailors from ships docked in the port, had been rescued by Russian forces and Donbass separatists.

Ukrainian officials deny that Russia has taken control of the city.

Mariupol is a strategic city on the Azov Sea, straddling the land corridor linking the Crimean peninsula with the separatist regions of eastern Ukraine. Full control of Mariupol would be a major strategic victory for Russia, opening a land corridor from Crimea to the pro-Russian separatist territories of eastern Ukraine.

The Azovstal Iron and Steel Plant is located in the southern industrial zone of the city, isolated from the densely populated inner city areas. Azovstal was built during the Soviet era and is also one of the largest metallurgical plants in Europe, stretching over 10.3 km.²along the city's riverbank. Before becoming the last defensive stronghold in Mariupol, Azovstal played an important role in the city's economy, providing livelihoods for tens of thousands of people.

Major Serhii Volyna - Commander of the 36th Independent Marine Brigade of Ukraine said that the forces entrenched in the tunnel system under the factory included members of the Azoz Battalion, foreign mercenaries and hundreds of civilians.

The Russian Ministry of Defense has twice issued ultimatums to Ukrainian defense forces inside the factory to lay down their weapons and surrender, but they have both refused, declaring "resistance to the end." The factory is currently completely cut off from outside supplies.

"We have prepared about 90 buses and 25 ambulances for them. No one has left the Azovstal plant," the Russian defense minister said, adding that cameras had been installed in the area to monitor the situation and about 100 civilians from other areas had taken the opportunity to evacuate.

New Russian offensives in Ukraine.