The besieged city of Mariupol remains closed to anyone trying to enter, and it is “very dangerous” for anyone trying to leave, an aide to the mayor said Friday.

Russia had announced a humanitarian corridor for Mariupol for Friday, but it had not been opened in the morning, according to the assistant. Moreover, according to him, “since yesterday, the occupiers have not allowed humanitarian aid, even in small quantities.”

On Thursday, Russia promised a ceasefire for “humanitarian purposes” at Mariupol. Ukraine sent 45 buses to the city to evacuate civilians, but officials say they never arrived. Instead, Russian troops are said to have stopped the buses. Russia and Ukraine blame each other for humanitarian corridors that are not going ahead despite agreements.

According to local authorities, in Mariupol, surrounded for weeks by Russian troops, up to 170,000 people are detained in appalling conditions. A large part of the city was destroyed or damaged by the war. 5000 are also said to have been killed.

“Everyone knows a humanitarian catastrophe is going on there,” President Volodimir Zelenski said on Thursday.