Approximately 350,000 people remain trapped in Mariupol, the city in southeastern Ukraine that has been besieged by Russian troops since March 1, according to a local official.

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“Considering there are 540,000 residents and around 150,000 people evacuated in the first three days when it was still safe to do so, we estimate around 350,000 people to be stuck in Mariupol,” Petro Andriushchenko, adviser to the Mariupol mayor, said on Ukrainian television Monday.

Several official attempts in recent days to build safe corridors and evacuate inhabitants from Mariupol have failed. According to officials, a major convoy of humanitarian aid that was supposed to come on Sunday has yet to arrive in the city as of Monday.

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He added, “Most of the people are staying in the basements and shelters in inhumane conditions. With no food, no water, no electricity, no heating,” People were melting snow and disassembling the heating system to acquire water to drink, he claimed.

Concerning civilian casualties, Andriushchenko stated that the figures collected from police and calculated by medical facilities were most likely wrong. He stated that as of Sunday, 1,800 individuals had been confirmed murdered.

Oleksiy Arestovych, an adviser in President Volodymyr Zelensky‘s administration, stated on Monday that the Russian shelling of Mariupol had resulted in almost 2,500 deaths.

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Mariupol is located on the Azov Sea, around 100 kilometres from Donetsk, which Russian President Vladimir Putin has recently acknowledged as an independent republic.

If taken, this city would play an important role in the hypothetical land corridor between Russia and the Crimean peninsula. Notably, in March 2014, Russia took Crimea from Ukraine.

This is consistent with Russia’s concept of territorial continuity, in which it intends to connect the Black Sea peninsula and the rebel territories of Ukraine’s east, Donetsk and Luhansk, which Moscow now considers autonomous.

However, losing Mariupol means losing access to the Azov Sea “in an economic sense,” according to Radio Free Europe/Radio Liberty.