A picture taken with a mobile phote shows smoke rising near the Chernobyl nuclear power plant on June 4, 2018, after a wildfire has broken out at the exclusion zone around Chernobyl nuclear power plant

A forest fire that had raged for three days in the restricted zone around Chernobyl, scene of the world's worst nuclear accident in 1986, was put out Thursday and no increase in radiation in the air was detected, authorities said.

"The fire in the exclusion zone was put out" in the evening, the Ukrainian emergency situations service said in a statement.

"Radiation levels in Kiev, Chernobyl and the power plant have not exceeded normal levels," it added.

Chernobyl polluted a big part of Europe when its fourth reactor exploded in April 1986, with the area immediately around the power plant the worst affected with a 30-kilometre uninhabited exclusion zone surrounding the power plant.

The fire broke out Tuesday morning in a dry grassy area of the exclusion zone, before moving to a forested area 10 kilometres from the power plant, burning some 10 to 15 hectares in total, according to Ukrainian authorities.

A 30 kilometres radius around the power station is still an exclusion zone where people are not allowed to live.

The three other reactors at Chernobyl continued to generate electricity until the station finally closed in 2000. A giant protective dome was put in place over the fourth reactor in 2016.