Security officials say interrogations revealed the German of Egyptian origin believed in the extremist ideology of the Islamic State group. Egyptian authorities did not provide any evidence to support their allegations.
Another detained German, an 18-year-old from Giessen, is still in custody. He was stopped at Luxor airport on Dec. 17 and authorities also accuse him of supporting IS ideology that advocates terrorism. No evidence was released in his case either.
Christofer Burger, a Foreign Ministry spokesman, told reporters in Berlin that Egyptian authorities confirmed the Giessen resident is in their custody, but that the German embassy had not yet been granted consular access to him.
"All we have received from the authorities is the confirmation that he is in custody," he said. Officials spoke on condition of anonymity as they weren't authorized to brief reporters. The German Embassy in Cairo could not be immediately reached for comment.
German media have reported that both young men had been on trips intending to visit their grandparents. Egypt's Supreme State Security Prosecution is now leading an investigation into the men.
Associated Press writer David Rising in Berlin contributed.