Russia is using a nuclear reactor in Ukraine as cover to allow it to launch strikes on Ukrainian forces without fear of reprisal, US Secretary of State Antony Blinken said on Monday.

Addressing reporters at the UN's New York headquarters, Blinken said Russian forces have been using the Zaporizhzhia nuclear power plant, which they seized from Ukraine in March, as a "nuclear shield," describing the tactic as "the height of irresponsibility."

Russian forces are "firing on Ukrainians from around the plant, and of course the Ukrainians cannot and will not fire back less there be a terrible accident involving a nuclear plant," he said.

- It's vitally important that the IAEA get access to understand what's happening in these facilities and to make sure that they continue to be used in ways that uphold all of the necessary commitments on safety, and security of the plants - Blinken added, referring to the International Atomic Energy Agency.

The New York Times first reported on Russia's alleged use of the Zaporizhzhia plant, which is Europe's largest, as "cover." Blinken said the report is "credible."

Russian shelling from the facility is "complicating" Ukrainian plans to mount a counteroffensive in the southern areas of the country occupied by Russian forces, the Times reported.