Militant threat on Eiffel Tower intercepted: source

LISBON (Reuters) - Portuguese air traffic authorities have intercepted a message describing a militant threat against the Eiffel Tower and have passed it to French authorities, a Portuguese source said on Friday.

"It is true we intercepted a conversation with terrorist threats to the Eiffel Tower yesterday," the source, who asked not to be named, told Reuters. "Our air force informed the French air force of this matter.

Paris police referred inquiries to the Eiffel Tower where nobody was immediately available for comment.

French daily Le Monde reported on Friday that intelligence services were tracking the authors of the message.

The newspaper said Portuguese air traffic authorities had intercepted a "vague and confused" short wave radio message on Thursday, according to a police source.

The French capital is already at its second highest security alert level and further public security measures would serve little purpose, Le Monde quoted police as saying.

"We've been at red for several months. It's the highest level before scarlet alert which is implemented when there are attacks," the local police headquarters told the newspaper.

The Eiffel Tower is one of France's best-known sights and welcomes millions of tourists each year.

Since it was built for the 1889 World Fair, over 230 million people have climbed its 1,665 steps or taken the elevators to admire the views from the top of the 324-metre (1,063 ft) high structure.

Several apparent threats against Paris and prominent personalities have also been identified on an Islamist website and are being taken seriously following the murder of four French tourists in Mauretania last month, French media said.

(Reporting by James Mackenzie and Henrique Almeida; Editing by Caroline Drees)