German officials say a number of Germans are traveling to Afghanistan and Pakistan for militant training, and several have returned to live in Germany.
The information comes amid reports that a U.S. missile strike in Pakistan killed five German militants near the town of Mir Ali in North Waziristan, an area known for its links to al-Qaida.
Pakistani officials say the drone strike killed at least eight militants, including five Germans.
U.S. officials believe that a cell of German and British militants are behind a recent terror plot to attack several European cities.
Germany has said it has concrete evidence that at least 70 Germans have undergone paramilitary training in Pakistan and Afghanistan and that a third of them have returned.
Kenyan authorities said Tuesday they had arrested a German terrorism suspect who was reportedly on his way to Somalia. Sascha Alessadro Bottcher, a Muslim convert, was deported back to Germany.
Somalia's government is battling insurgent groups al-Shabab and Hizbul Islam, which are trying to turn Somalia into a strict Islamic state.
Security officials in Europe and the United States for days have discussed the possibility of armed attackers staging a repeat in Europe of the 2008 assault against Mumbai, India, that left 166 people dead and scores wounded.
Unlike Britain, Japan, Sweden and the United States, German security officials have not issued new travel warnings to their nationals. Germany also has not raised the country's terror alert.
Some information for this report was provided by AP and Reuters.