BERLIN—German authorities have launched a large-scale search in Berlin for two suspected suicide bombers, according to people close to the investigation.

The suspected Islamic extremists are believed to be planning an attack on a prominent location in the German capital in the coming weeks, according to one of the people familiar with the investigation. Police are combing through travel and visa records and scrutinizing new arrivals from the Middle East and South Asia as part of the search, this person said.

Concerns of an imminent attack prompted a public warning by Germany's interior ministry this week that terrorists plan to strike one or more crowded public locations in major German cities by the end of this month.

Authorities believe the two men they are searching for in Berlin arrived in the German capital about six weeks ago from the Waziristan region of Pakistan, according to a person familiar with the investigation.

The suspects are trying to avoid detection by wearing western clothes, avoiding mosques, and changing their hideouts regularly, according the people. Authorities believe the two men are waiting for a shipment of bomb detonators that may be transported from Turkey to Berlin by unwitting friends or relatives.

The German news magazine Der Spiegel reported Saturday that police fear the attack involving bombs and small arms could be aimed the German parliament building, known as the Reichstag. A senior intelligence official said the Reichstag has not been specifically named as a terrorist target, although it fits the outlines of the alleged terrorist goal of attacking an "important office."

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