An investigation into the sudden plunge of the Serbian president’s plane last week has revealed that it was due to the co-pilot spilling coffee on the instruments panel.

The co-pilot accidentally activated the emergency slot extension when trying to clean the coffee from the panel, according to the report. That caused the plane to dive and triggered the brief shutdown of one of the engines, which triggered panic among passengers. The captain then stabilised the aircraft and returned to the Serbian capital, Belgrade.

Initially, President Tomislav Nikolić’s press office said on Friday that the plane made an emergency return because of an engine failure. Nikolić was en route to the Vatican for an official visit, which was cancelled.

The co-pilot has been suspended.