A huge forest fire in Ukraine that has been raging for more than a week is now just one kilometer from the defunct Chernobyl nuclear power plant and poses a radiation risk, Greenpeace Russia warned on Monday, citing satellite images.

Ukraine's Emergency Situations Service said it was still fighting the fires, but that the situation was under control.

Video footage shot by Reuters on Sunday showed plumes of black smoke billowing into the sky and trees still ablaze, with firefighters in helicopters trying to put out the fires.