Forest fires raged Tuesday in the contaminated area near the Chernobyl nuclear power plant, but officials insisted there is no radiation threat.
Hundreds of firefighters backed by aircraft have been battling several forest fires around Chernobyl since last week. They managed to contain the initial blazes, but new fires are now raging close to the decommissioned plant.
Volodymyr Demchuk of Ukraine's state Emergencies Service insisted that the situation is under control.
"There is no threat to the Chernobyl nuclear power plant, waste fuel storage or other critical facilities," he said.
The emergencies service said radiation levels in the capital, Kyiv, about 100 kilometers (60 miles) south of the plant, were within norms.
Activists warned, however, that the blazes were getting dangerously close to waste storage facilities.
Yaroslav Yemelyanenko, a member of the public council under the state agency in charge of the closed zone around the plant, said one fire was raging within 2 kilometers (about 1.2 miles) from one of the radioactive waste depots.
"The situation is critical," he said on Facebook.
Last week, officials said they tracked down a person suspected of triggering the blaze by setting dry grass on fire in the area. The 27-year-old man said he burned grass 'for fun' and then failed to extinguish the fire when the wind caused it to expand quickly.
On Monday, police said that another local resident burned waste and accidentally set dry grass ablaze, triggering another devastating forest fire. They said he failed to report the fire to the authorities.
The 2,600-square-kilometer (1,000-square-mile) Chernobyl Exclusion Zone was established after the April 1986 disaster at the plant that sent a cloud of radioactive fallout over much of Europe. The zone is largely unpopulated, although about 200 people have remained despite orders to leave.
Blazes in the area have been a regular occurrence. They often start when residents set dry grass on fire in the early spring - a widespread practice in Ukraine, Russia and some other ex-Soviet nations that often leads to devastating forest fires.
'No open fire'
Ukraine said on Tuesday only small isolated fires remain at the scene of a blaze that erupted 10 days ago in the Chernobyl exclusion zone, scene of the world's worst nuclear accident in 1986.
"There is no open fire," the emergency services said in a statement, adding that radiation levels are within the norm.
Police have said the fire was sparked on April 4 by a man burning dry grass near the exclusion zone around the ruined reactor. The flames spread quickly, fanned by strong winds.
Kiev has mobilised helicopters and more than 400 firefighters, with planes dropping hundreds of tonnes of water on the fire.
Ukraine President Volodymyr Zelensky said late on Monday he is "closely" following the situation and was "grateful for the courage" of the firefighters.
On Tuesday the president said he will hear a report from the chairman of the emergency service and that "society should know the truth and be safe."
Oleksandr Syrota, head of the Chernobyl information centre, welcomed reports of rain in the exclusion zone as "good news" on Facebook.
The interior ministry's spokesperson said rain "has greatly helped rescuers who have been fighting with fire in the area for over a week".
While forest fires are common in the exclusion zone, Greenpeace Russia said Monday 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 just 1.5 kilometres (less than a mile) from the protective dome over the ruined reactor.
Sergiy Zibtsev, head of the Regional Eastern European Fire Monitoring Center, told AFP that the fire is "super-huge" and "unpredictable".
"In the west of the exclusion zone it has already covered 20,000 hectares (50,000 acres) by our calculations."
The Ukrainian emergency service has not provided recent figures on the size of the fire, but said that "there is no threat to the Chernobyl nuclear power plant and the storage facilities".
Government agencies have insisted the fire has not caused a spike in radiation levels.
After the 1986 explosion, the three other reactors at Chernobyl continued to generate electricity until the power station finally closed in 2000. A giant protective dome was put in place over the fourth reactor in 2016.