KYIV, Ukraine -- The fire at Europe's largest nuclear power plant has been extinguished, Ukrainian emergency services said Friday, after Kyiv blamed Russian military shelling for the blaze.

Ukrainian President Volodymyr Zelensky accused Moscow of resorting to "nuclear terror" and wanting to "repeat" the Chernobyl disaster after he said invading Russian forces deliberately attacked the nuclear power plant.

Ukraine's emergency services said it was able to put out the fire after the Russian military eventually allowed rescuers to access the site.

"At 06:20 (04:20 GMT) the fire in the training building of Zaporizhzhia NPP in Energodar was extinguished. There are no victims," the emergency services said in a statement on Facebook.

Zelensky had earlier begged world leaders to wake up and prevent Europe from "dying from a nuclear disaster" after Russian forces attacked the continent's largest plant.

"No country other than Russia has ever fired on nuclear power units," he said in a video message released by his office.

"This is the first time in our history. In the history of mankind. The terrorist state now resorted to nuclear terror."

Zelensky said the troops had knowingly fired on the nuclear facility.

"These are tanks equipped with thermal imagers, so they know where they are shooting," said Zelensky.

The station at Zaporizhzhia, an industrial city in the southeast, supplies an estimated 40 percent of the country's nuclear power and, according to Zelensky, houses six of Ukraine's 15 reactors.

Ukrainian emergency services had earlier raised alarm that Russian troops were preventing them from reaching the fire at the plant.

"The invaders are not authorising Ukrainian public rescue units to begin extinguishing the fire," the emergency services said on Facebook, stating that the blaze had affected a "training building" and that only one of the reactors was operational.

Local officials had reassured the UN's atomic watchdog that "essential" equipment at the station was unaffected and radiation levels were normal.

Ukraine's nuclear facilities have been a main point of concern after Russia's military invaded the country last week and began bombarding cities with shells and missiles.

The Zaporizhzhia plant is located in the southern Ukraine steppe on the Dnieper River, around 525 kilometres (325 miles) south of Chernobyl.

"If there is an explosion, it is the end of everything. The end of Europe," Zelensky warned. "Only immediate European action can stop Russian troops."