Russian troops are attacking 'kindergartens' - WATCH Ukraine's President Zelensky's statement

Ukrainian leader Volodymyr Zelensky has accused Russian forces of attacking non-military targets.

Zelensky said: "They [Russian troops] are fighting against all living beings.

"They are fighting against kindergartens, residential buildings and ambulances.

"They use rocket artillery, missiles in city districts where there are not, and never were, any military facilities."

These claims follow reports from the World Health Organisation that Ukrainian hospitals may run out of essential oxygen within twenty-four hours.

The WHO said dwindling oxygen supplies are reaching a "very dangerous point" due to transportation disruption in the wake of Russia’s military invasion.

"The majority of hospitals could exhaust their oxygen reserves within the next 24 hours. Some have already run out. This puts thousands of lives at risk," said WHO director-general Tedros Adhanom Ghebreyesus and WHO Europe regional director Dr Hans Kluge in a joint statement.

Wladimir Klitschko, Ukrainian boxing legend and brother of Kyiv's mayor, released a video in which he called on global leaders to intervene in the conflict.

The former heavyweight champion of the world simply said: "Don't wait. Act now. Stop this war."