KIEV, Ukraine (AP) — There has been no change in background radiation levels in the Ukrainian capital as a result of nighttime fires in woodlands in the exclusion zone around the destroyed Chernobyl nuclear power plant, Ukrainian authorities said Wednesday.
The emergency services agency said in a statement that isotope levels in surface soil and water are within the norm.
Authorities in neighboring Belarus, which lies adjacent to the exclusion zone, said it too had detected no change in radiation in its southern regions.
Kiev, the capital of Ukraine, lies less than 100 kilometers (60 miles) downriver from the zone around Chernobyl, which was heavily contaminated by radiation from the 1986 reactor explosion and fire.
A 30-kilometer (18.6-mile) zone around the plant is off-limits to most people except for workers constructing a new shelter to cover the destroyed reactor's building, and to visitors on short trips.
Authorities said Tuesday evening's fire swept through 400 hectares (1.5 square miles) of woodland.
Belarus was hardest hit by the Chernobyl accident with 70 percent of the country's territory affected to some extent by radiation.
Yury Golikov, head of the information department at the Belarus state center for radiation pollution, said that a blaze at least half the size of that seen in 1986 would be required to lead to a change in background radiation levels.
Ukrainian officials warned Tuesday evening that the situation could be complicated by the strong winds blowing the fire in the direction of the plant. But Interior Minister Arsen Avakov said the winds had died down later in the night.
Security was tightened around the perimeter of the exclusion zone amid suspicions the blaze had been sparked intentionally, Avakov said.
"Patrols have been stepped up. National Guard and Interior Ministry units have been placed on high alert," he said in a statement.
Yuras Karmanau in Minsk, Belarus, contributed to this report.