A Ukrainian official said on Thursday that a convoy of buses en route to the besieged Ukrainian city of Mariupol had been held up at a Russian checkpoint in Vasylivka, a city between the Ukrainian-held city of Zaporizhzhia and the Russian-held city of Berdiansk.
"Our task is to open a humanitarian corridor and help people survive, especially civilians — women, children, the elderly," according to Iryna Vereshchuk, Ukrainian minister of reintegration of temporarily occupied territories.
"As of 12:30 pm (5:30 am EST), 45 buses left Zaporizhzhia for Berdiansk. As of this moment, they are at Vasylivka checkpoint, and the Russian Federation is again not letting our buses through. Again and again, we demand that the entire world community focus its attention and help people get out of occupied Mariupol," Vereshchuk said.
The International Committee of the Red Cross said Thursday it was preparing to facilitate the safe passage of civilians from Mariupol on Friday.
Vereshchuk said about 100,000 people requiring immediate evacuation remain in the city, out of a pre-war population of more than 400,000.
"That is, another 100,000 women, children, the elderly, and people with disabilities who need our and the world's help," she said.
Vereshchuk claimed that 45,000 Ukrainian citizens have been forcibly deported to Russia, a figure CNN could not immediately verify. The Russian military says that thousands have been "evacuated" to Russia from separatist-held regions and "dangerous areas" of Ukraine.
Earlier today, Mariupol Deputy Mayor Sergei Orlov told CNN's John Berman that buses were moving through the evacuation corridor.
Orlov said up to 1,500-2,000 will be able to evacuate the city between today and tomorrow.
He added there are "constant street battles" in the city, but the Ukrainian army still controls the city center.
People remaining in Mariupol are "living like mouse. They are living underground in shelters, bomb shelters below. So people just do their best to be alive in this situation," he said.
CNN's Adrienne Vogt contributed to this post.