Nearly a hundred children have died in the war that followed Russia's invasion of Ukraine, President Volodymyr Zelenskyy told Canadian lawmakers on Tuesday.

The southern Ukrainian city of Mariupol was left without means of communication and was nearly running out of food, Zelenskiy said in a virtual address to Canadian lawmakers.

He added that 97 children had been reported dead in total since the war began.

Meanwhile, Fox News cameraman Pierre Zakrzewski was killed in Ukraine after the vehicle in which he was traveling was struck by incoming fire, the US network reported on its website.

Zakrzewski was reporting with another Fox News journalist, Benjamin Hall, on Monday when they came under attack near the capital Kyiv, according to a video on the website. Hall remains in hospital, it added.