A Muslim couple from Tokyo who said they wanted to visit areas controlled by the Islamic State militant group have been missing since leaving Japan for Turkey in November, sources said Monday.
The Algerian French man and his Japanese wife, both in their 20s, were questioned by security authorities after their plans became known.
The pair told officials they wanted to travel to the region for "humanitarian assistance" and denied planning to join the fighting.
Both the Japanese government and the French Embassy in Tokyo tried to dissuade them from their travel plans, but in early November they left from Narita International Airport and entered Turkey, the sources said.
They added that it is not known whether the couple actually entered Syria, which borders Turkey, as checkpoints in the area are not functioning properly.
Officials said the Japanese government is trying to identify their whereabouts.