"Terrorists" who attack U.S. interests have no place to hide, U.S. Defense Secretary Leon Panetta said Friday as fears grew for the dozens of foreigners taken hostage by Islamists at a gas plant in Algeria.

"Those who would wantonly attack our country and our people will have no place to hide," he said in a speech in
London , adding that Washington working to secure the safe return of an unknown number of Americans who had been at the plant.