Paris police reopened the Eiffel Tower on Tuesday to the public after tourists were evacuated following the second bomb alert this month at one of the world's most visited sites.
The latest alert came amid official warnings that France faces a serious threat of imminent terrorist attack and just a day after a major Paris train station was evacuated after a bomb alert that proved to be a false alarm.
Police said the operator of the Eiffel Tower had received a phone call from a public telephone at 6:40 pm (1640 GMT) warning of a bomb.
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Police experts scoured the 324-metre (1,063-feet) high tower for suspect devices and the area around the Eiffel tower was cordoned off.
Police on September 14 evacuated around 2,000 people from the tower and the park surrounding it following a bomb alert that also turned out to be a false alarm.
The French national police chief said last week he was concerned about two types of threat by Islamist extremists -- an assassination bid on an important figure or an attack on a crowded area like a metro train or department store.
Asked last week about reports that an attack might be imminent, Interior Minister Brice Hortefeux said: "The threat is real, we have stepped up our vigilance."
Separately, a source close to the ministry confirmed that police were probing reports that a female suicide bomber may be preparing a strike in Paris, but added: "That's not necessarily the most worrying thing."
Instead, he explained, Paris was concerned with intelligence received from an allied foreign spy agency that Al-Qaeda's North African branch, Al-Qaeda in the Islamic Maghreb (AQIM), was planning an "imminent" attack in France.
The Algerian intelligence agency has passed on warnings about militants heading to French to carry out attacks, and officials say there is also evidence of Jihadi fighters returning from Afghanistan and Pakistan.
