"Search and rescue efforts are ongoing," an intelligence source said, when asked about a photo of the hostages that surfaced on the internet.
The photo showed Stefan Viktor Okonek, 74, and Henrike Dielen, 42, holding what appears to be a German flag and surrounded by 10 armed men with cloth or scarves partly covering their faces.
The source said the photo appears to be authentic, but declined to give more details.
Mr Okonek and Mr Dielen were allegedly seized by Abu Sayyaf rebels from their yacht off the western province of Palawan on April 25.
They were believed to have been brought to Jolo island, 1,000 kilometres south of Manila, a stronghold of the Abu Sayyaf, which has been blamed for previous kidnappings of foreign hostages.
A Filipino hostage freed by the Abu Sayyaf last month told authorities that he saw the German nationals during his time in captivity.