A security official in a second European country confirmed the information, adding: "From what I understand, a specific target has not been established."

European security services, including in Norway, have warned in recent years of homegrown, radicalized Muslims traveling to terror training camps in conflict zones. Many of the known cases involve young men with family roots in Muslim countries.

But the latest case involves a man in his 30s with no immigrant background, the officials said. After converting to Islam in 2008, he quickly became radicalized and traveled to Yemen to receive terror training, one of the officials said. The man spent "some months" in Yemen and is still believed to be there, he said.

The official said the man has no criminal record, which would also make him an ideal recruit for Al Qaeda.

"Not even a parking ticket," he said. "He's completely clean and he can travel anywhere."