Five men broke into the Hotel Inatel in Albufeira in the early hours of July 12 and, according to police, attempted to break into the safe which contained a large sum of money.
The five robbers were armed, one with a machine gun.
A spokesman from the police said: “As the robbers were preparing to rob the safe, a night guard appeared and was attacked by the group but managed to escape. After that encounter, the men gave up trying to open the safe.”
PJ police are now investigating the case.