A plaster on his eye, eight-year-old Dima Kasyanov lies unconscious on a hospital bed in Ukraine's second city Kharkiv after a Russian missile blasted through his home.

He was in his family flat when it hit on Monday, sending shrapnel shooting through his upper jaw and into the base of his neck, his doctor Oleksandre Dukhovsky says.

"For two days, we pumped ash out of his stomach. He still has cinders in his lungs," says the head of the city's paediatric neurosurgery centre.

"But he is stable. Slowly we are getting there," says the surgeon, as he emerges from operating on another, a 52-year-old man.

Since Russia invaded its pro-Western neighbour on February 24, at least 78 children have been killed and more than 100 wounded, Ukraine's ombudswoman Lyudmyla Denisova says.

The UN children's agency UNICEF has warned the war threatens the lives and well-being of the country's 7.5 million children.

More than 100 children have been wounded in Ukraine since Russia invaded last month, Ukraine's ombudswoman Lyudmyla Denisova says
More than 100 children have been wounded in Ukraine since Russia invaded last month, Ukraine's ombudswoman Lyudmyla Denisova says AFP / Sergey BOBOK

More than one million children have fled the country, it says, among more than two million Ukrainians who have crossed into next-door countries to safety.

In the eastern city of Kharkiv near the Russian border, a nurse checks Dima's vitals on a screen near his bed.

Outside the intensive care unit, his parents Sergei and Olena have managed to bring in medicine, as medical supplies dwindle nationwide.

"We live at the hospital. Our flat no longer exists," says Olena.

Seven-year-old Vova suffered a brain injury after shots were fired at his family's car
Seven-year-old Vova suffered a brain injury after shots were fired at his family's car AFP / Sergey BOBOK

In what remains of the family home, part of the floor has collapsed and the rest is covered in debris.

Water seeps through a hole in the ceiling, and bits of concrete dangle dangerously.

Several other apartments in the ten-storey Soviet-era building were also destroyed, an AFP journalist said.

Olena says she cannot wait to whisk her son away.

"We want to speak to the doctor to know when we can move him," she says.

"Volunteers have suggested taking him to Germany to continue treating him there."

Not far off in the same hospital, seven-year-old Vova has just been moved out of the intensive care unit, his head wrapped in medical gauze.

Dukhovsky, the doctor, says Vova was carried in with a brain lesion and had to be operated on immediately.

"It was really bad at first, but now he has started to speak and eat again," he says.

By his bedside, the young boy's father tends to him, giving him something to drink using a syringe.

"They shot at our car from a (Ukrainian) check-point," he says.

"My wife was killed," and Vova was badly wounded.

But "his three-year-old brother is OK. He's here, in the basement" shelter, because the bombardment is relentless.