People visit a deserted radar station near the Chernobyl nuclear power plant in Ukraine, Nov. 12, 2019. (Xinhua)

Hundreds of firefighters on Monday battled a forest blaze in Ukraine's Chernobyl exclusion zone while officials insisted there was no risk to the ruined reactor and nearby storage facilities for nuclear waste.

"There is no threat to the Chernobyl nuclear power plant and the storage facilities," Volodymyr Demchuk, a senior official from Ukraine's emergency service, said in a video statement late Monday.

The fire broke out 10 days ago at the scene of the world's worst nuclear accident in 1986. 

Kiev has mobilized helicopters and more than 400 firefighters, with planes dropping tons of water on the fire.

Demchuk said firefighters are now focused on stopping the spread. While forest fires are common in the exclusion zone, Greenpeace Russia said that this is the worst since the 1986 nuclear explosion.

The environmental campaign group said that analysis of satellite images showed the fire at its closest point was 1.5 kilometers from the protective dome over the ruined reactor. 

Sergiy Zibtsev, head of the Regional Eastern European Fire Monitoring Center, said that the fire is "super-huge" and "unpredictable."

The Ukrainian emergency service has not provided recent figures on the size of the fire.

Yaroslav Yemelianenko, head of the Chernobyl tour guide association, said the fire had reached the ghost town of Pripyat, a city near Chernobyl whose population of around 50,000 was evacuated after the explosion.

Ukraine's deputy interior minister Anton Gerashchenko said there is no danger for the nuclear waste storage facilities.