A video posted on twitter on Sunday showed ten armed masked men and an unmasked man holding a machete to the neck of one of the four hostages abducted from the “Island Garden City” on Samal Island in September.
Behind the gunman was a flag believed to be associated with the Islamic State group.
On Wednesday a Philippine military spokesman said that the video was being verified but appeared to be authentic.
Authorities said that no group has officially claimed responsibility for their abduction and they have not identified any single group with finality.
Robert Hall, John Ridsdel and Kjartan Sekkingstad make statements during the video calling for military operations against the rebels to cease and telling of the grave danger they face. Marites Flor, the only woman abducted, remained silent throughout the footage.
The Philippine military has declined to comment on whether the military was conducting operations against any rebel groups in Mindanao.