A Ukrainian official on Saturday said Russia had resumed its attempts to storm the resistance stronghold under the Azovstal steel plant in Mariupol where thousands of Ukrainian civilians and soldiers remain holed up. 

"The enemy is trying to strangle the final resistance of the defenders of Mariupol in the Azovstal area," Ukrainian presidential adviser Oleksiy Arestovych said in a televised address according to Reuters. 

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Smoke rises above Azovstal steelworks, in Mariupol, Ukraine, in this still image obtained from a recent drone video posted on social media. 

Smoke rises above Azovstal steelworks, in Mariupol, Ukraine, in this still image obtained from a recent drone video posted on social media.  (MARIUPOL CITY COUNCIL/via REUTERS)

The advisor's comments come just days after Russian President Vladimir Putin said he didn’t believe a ground assault on the plant was "necessary."

Putin instead called on his troops to instate a blockade to put pressure on Ukrainian forces to surrender as supplies to civilians run short. 

"One does not have to climb into these catacombs and crawl there underground around these industrial objects," he said. "Block this industrial zone in such a way that even a fly could not fly through."

But despite Putin’s claims, Russian forces continued to pummel the steel plant with a barrage of heavy bombing. 

"Every day they drop several bombs on Azovstal, despite false promises not to touch the defenders," Petro Andryushchenko, adviser to Mariupol’s mayor, told the Associated Press Friday.

"Fighting, shelling, bombing do not stop," he added. 

Donetsk Ukraine

An armed serviceman of Donetsk People's Republic militia walks past a building damaged during fighting in Mariupol on Wednesday. (AP/Alexei Alexandrov)

Roughly 1,000 civilians and soldiers are believed to be holed up in the tunnels and footage released by an Azov military unit showed that large numbers of women and children are living under the plant. 

UKRAINE DISPUTES RUSSIA'S CLAIM WILL NOT STORM MARIUPOL STEEL PLANT FULL OF CIVILIANS

Ukrainian officials have repeatedly called on the Russians to stop their barrage on the plant and allow civilian evacuation routes to be carried out.

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In addition to the continued bombing campaign, Ukrainian intelligence said Friday it believed Russia would launch a ground offensive by deploying soldiers from its elite military units along with personnel from its Federal Security Service – a successor intelligence agency to Russia’s infamous KGB.

"According to our data, they plan to deploy Russian Guards and other parts of the military apparatus, including the Federal Security Service, to continue their assault on the plant and destroy our resistance," Representative of Ukraine’s Central Intelligence Directorate Vadym Skibitskyi told reporters.