Colonel Volker Bauersachs salutes during a memorial service for two German soldiers of the Combat Helicopter Regiment 36 who died on July 26, 2017 on a mission in Mali, during a memorial service at the Dom of St. Peter in Fritzlar, Germany, August 3, 2017. REUTERS/Swen Pfoertner/POOL

BERLIN (Reuters) - German investigators may need months to determine what caused an Airbus military helicopter to crash during a peacekeeping mission in Mali, killing both crew members, defense ministry spokesman Jens Flosdorff said on Wednesday.

German military authorities were working closely with U.N. officials, the manufacturer and other countries that operate the helicopters after an interim report by the Germany military showed that the Tiger helicopter began to break up while in flight, losing its rotor, Flosdorff said.

Airbus declined comment on the interim report.

“We are aware of the interim report and are committed to support the investigation as and when required by the authorities – in the meantime, we will not comment further,” an Airbus spokesman said.

Flosdorff told a news conference that both parts of the helicopter’s flight data and cockpit voice recorders had been retrieved, but only one could be analyzed. He said it was unclear what caused the rotor to come off as the helicopter went down in a steep descent.

Defense Minister Ursula von der Leyen told the Passauer Neue Presse newspaper on Wednesday there were no indications that it “had to do with the training of the pilots.”

An in-air break-up could suggest that maintenance or manufacturing issues contributed to the crash, although the report said it was too early to speculate about any causes.

The deployment of the Tiger helicopters to Mali earlier this year was controversial since the aircraft required extra maintenance given the high heat in the desert country but officials said at the time the four vehicles had been performing normally.