France, Belgium on Alert for Extremists Plotting Attacks

French police and anti-terrorism investigators have been alerted to the possibility that small groups of extremists have left Syria for France and Belgium with plans to stage attacks.

Belgian intelligence services sent a note to French counterparts about the possible groups, and it was sent to police across France on Tuesday, a French security official said Wednesday.

French authorities remain "very cautious" about the information because they receive such notes routinely, the official said.