European Council President Charles Michel has reported having a phone call with Russian President Vladimir Putin on Friday and having called for the immediate opening of humanitarian corridors in Ukrainian citizens as Orthodox Easter is approaching.

"Call with President Putin. Strongly urged for immediate humanitarian access and safe passage from Mariupol and other besieged cities all the more on the occasion of Orthodox Easter," Michel said on Twitter.

Michel said that he "firmly reiterated the EU's position: support for Ukraine and her sovereignty, condemnation and sanctions for Russia's aggression."

"Our unity, principles and values are inviolable," he said.