LONDON — Intelligence officials intercepted a credible terror plot against Britain and France, raising security fears at the Eiffel Tower on Tuesday, but failed to raise the overall threat level in either country.The Eiffel Tower was briefly evacuated Tuesday evening after officials received a bomb threat called in from a telephone booth. It was the second such alert at the monument in two weeks.RELATED:France: Railway station evacuated after bomb scarePolice: Norway terror plot targeted Danish paperThe warning came as French officials were put on alert for possible terror attacks. British officials, too, have been aware of a possible attack but the terror threat warning has not changed from "severe.""There have been a succession of terror operations we've been dealing with over recent weeks but one to two that have preoccupied us," said one British government official who spoke on condition of anonymity because of the sensitivity of his work. "Still, it has not been to the degree that we have raised the threat level."Another British official, who spoke on the same terms, would not confirm the plot was "al-Qaida inspired" but said there was an "Islamist connection" and that the plots were in an early stage. No other details were given.German officials denied Tuesday they had intercepted threats, saying there had been no change to their threat level. In Paris, French police closed off the surroundings of the Eiffel Tower on Tuesday. Officers pulled red-and-white police tape across a bridge leading over the Seine River to the monument. Officers stood guard.Bomb experts combed through the 324-meter (1,063-foot) tower and found nothing unusual, the Paris police headquarters said. Tourists were let back inside about two hours after the structure was emptied.National Police Chief Frederic Pechenard said last week that authorities suspect al-Qaida's North African branch of plotting a bomb attack on a crowded location in France. His warning came after al-Qaida in the Islamic Maghreb, or AQIM, claimed responsibility for the September 16 abduction of five French nationals and two Africans in northern Niger.The French parliament voted this month to ban burqa-style Islamic veils in France, a subject that has prompted warnings by AQIM. Counter-terrorism officials said that is just one of several factors that contributed to the heightened threat.At the Eiffel Tower, an anonymous caller called in a warning to firefighters, the Paris police headquarters said. The company that runs the monument asked police to evacuate it.Police responded to a similar false alert at the tower on September 14, also following a phone threat. The bustling Saint Lazare train station in Paris was briefly evacuated and searched on Monday.