"The initial conclusions of the investigation launched the day after the accident (...) indicate that the crash occurred due to unfavourable weather conditions," General Lassina Doumbia said in a statement Wednesday evening.

The helicopter crashed in the middle of the night two kilometres (1.2 miles) north of Togolokaye, near the border with Burkina Faso -- an area where Ivory Coast has experienced several attacks by suspected jihadists.

Searchers were able to recover one of the helicopter's black boxes and found the remains of the five crew, consisting of "three (foreign) instructors" and two Ivorian airmen.

According to corroborating sources, the instructors were of Bulgarian nationality.

The Mi-24 is a heavy-duty helicopter gunship with transport for eight troops which first entered service in the Soviet Air Force in 1972.

The helicopter was on a "mission," said government spokesman Amadou Coulibaly, without giving further details.

A tribute will be paid to the Ivorian victims on Friday in Abidjan, the statement added, while a ceremony will be organised in honour of the foreign instructors before the repatriation of their bodies.