The U.N.'s nuclear watchdog on Monday laid out plans for establishing a security protection zone around Europe's largest nuclear power plant in the south of Ukraine.

The idea is to "keep things simple," said Rafael Mariano Grossi, the head of the International Atomic Energy Agency (IAEA). "What we need here, really, is to have Ukraine and Russia not attacking or not shelling at the plant."

The establishment of a security zone would be "a commitment that no military action will include or will imply aiming at the plant or at a radius affecting its normal operation."

The IAEA would ensure that the security perimeter is respected, Grossi added: "We have our monitors, inspectors there that can inform whether this is being observed or not."

Grossi said the plan is being discussed with Ukraine and Russia, and that he has "seen signs that they are interested in this agreement."

Ukrainian President Volodymyr Zelenskyy has repeatedly called for the full demilitarization of the plant and criticized Grossi for not speaking out more forcefully in favor of that idea.

Speaking at a press conference Monday, Grossi said: "I’m working within my mandate. I cannot get into areas that have to do with larger demilitarization or movement of troops."

The Zaporizhzhia nuclear power plant was seized by Russian troops in March near the start of the war, but is still operated by Ukrainian staff. Despite the restoration of a backup power line after it was damaged from shelling, the last operating unit at the plant was shut down on Sunday.

Grossi cautioned that "you cannot stay without any external source of power ... without damaging a number of parts, notably the turbine blades" of the reactors. Power is also required to keep their cooling systems running.

He added that, according to the agency's information, Ukraine is trying to "keep the plant operational" by restoring external power supply.

The IAEA chief also warned that as "the shelling continues," if a missile was to hit a reactor or the facilities where the spent nuclear fuel is stored, it "could have very serious consequences."