Petro Andryushchenko said in a post on Facebook on April 1 that Mariupol remained closed to an aid convoy trying to get badly needed supplies into the city, where tens of thousands of residents remain trapped with no electricity and few basic supplies.

"The city remains closed to entry and very dangerous to exit by private transport," Andryushchenko said.

"Since yesterday (March 31), Russian forces have categorically not allowed any humanitarian aid, even in small quantities, into the city. The reasons for such actions are still unclear, but this is disappointing. We do not see a real desire from the Russians to allow Mariupol residents to evacuate to other territory controlled by Ukraine," he added.

Ukrainian officials said on March 31 that a convoy of 45 buses was headed to Mariupol to deliver aid and leave with residents who have been trapped for weeks in the city. Russian military officials had said they were willing to adhere to a cease-fire to allow for the opening of a "humanitarian corridor."

Russian officials did not comment immediately on the situation, but several similar agreements have been reached in the past, only to collapse before their implementation.

The southern port city, home to some 430,000 people before the war, has seen intense fighting for weeks amid Russia’s invasion of Ukraine. Russian attacks have struck a maternity hospital, fire department locations, cultural venues, and civilian homes.

Tens of thousands of civilians are said to be trapped in the city with no electricity and extremely limited food and water supplies.

Russia launched its unprovoked attack on Ukraine on February 24.