President Zelensky has warned of a 'critical' situation at the Russian-occupied Zaporizhzhia nuclear plant which has now been off the grid for seven days straight.

The Ukrainian leader said one of the backup diesel generators used to maintain operations had 'malfunctioned' and that the blackout posed 'a threat to absolutely everyone'.

Moscow and Kyiv have repeatedly accused each other of risking a potentially devastating nuclear disaster by attacking the site.

In his daily address on Tuesday, President Zelensky said: 'The situation is critical.

'Due to Russian attacks, the plant has been cut off from its power supply and the electricity grid.