A Mi-8 helicopter of the Russian emergencies ministry has joined the effort to locate an An-2 plane that went missing in the vast Siberian republic of Yakutia, the ministry’s regional department has said.

"In order to participate in the search effort in the Kobyai district, a Mi-8 helicopter of the Russian emergencies ministry has departed to the area. Rescuers have special equipment and mountaineering tools," the department’s press service said.

Weather conditions in the search area - a high-altitude terrain - remain unfavorable, with low clouds and thick fog. An interdepartmental aviation commission to establish causes of the incident continues its work.

An An-2 plane went off radar screens and failed to arrive to its destination early on Tuesday. According to preliminary information, the plane had three people on board (two crew and one passenger), as well as one tonne of cargo. The plane’s emergency beacons did not work properly, so its current location is unknown. A criminal case has been launched on charges of violation of flight safety rules that resulted in deaths of two persons or more.