passage: London, England (CNN) -- Counterterrorism officers were Saturday searching the suspected London home of a man at the center of an incident aboard a U.S.-bound passenger flight that Britain's home secretary described as a "potentially serious security threat." The search, which focused on a upscale block in the heart of London's embassy district, followed the incident on Friday in which a Nigerian man ignited a small explosive device on a flight from Amsterdam to Detroit. The incident triggered an increase in security at UK airports and at Schiphol in Amsterdam, where the suspect in the attempted attack on a Northwest flight went through "normal security procedures," according to the security officials.
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  Police in London searching buildings in connection with Detroit plane incident
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  Nigerian man center of terror probe after igniting device on Northwest Airlines jet
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  Airline security stepped up in London, Amsterdam following incident
query: A U.S. administration official said the suspect did not undergo secondary screening in @placeholder, though Schiphol officials say all connecting passengers bound for the United States undergo secondary searches.
entities: Amsterdam Britain CNN Detroit England London Nigerian Northwest Northwest Airlines Schiphol U.S. UK