Ukrainian President Volodymyr Zelenskyy has expressed hope that civilian evacuations from the Azovstal steel plant in Mariupol will continue on Monday.

About 100 people reportedly evacuated from the besieged steel complex on Sunday when the operation began.

Zelenskyy said in a video message on Sunday that the evacuation corridor had finally started working, and more than a hundred civilians had already been evacuated.

He said he hopes "all the necessary conditions will be fulfilled on Monday to continue the release of the Mariupol people."

Russia's Defence Ministry said on Sunday that 80 civilians, including women and children, who had been detained by what it called Ukrainian nationalists, had been freed from the steel complex at the initiative of President Vladimir Putin.

Several hundred civilians are believed to be trapped in the plant. But it is uncertain whether they can all leave as Russian forces continue to pound eastern and southern areas of Ukraine.

The ministry also said that a missile attack had destroyed a runway at a military airfield in the southern port city of Odesa.

The ministry said Russian forces had attacked seven Ukrainian military facilities in the two eastern regions of Donetsk and Kharkiv.

The governor of the Donetsk region, Pavlo Kyrylenko, said that Russian forces struck a northern part of the region, killing four civilians and injuring 11.

The governor of the Kharkiv region, Oleh Synyehubov, said Russian attacks on a residential area had left three people dead and eight wounded.

UN Secretary-General Antonio Guterres met with Russian President Vladimir Putin in Moscow last Tuesday.

The UN said that the two agreed on the involvement of the UN and the Red Cross in the evacuation of civilians from Mariupol.