More from This is London:
The 1,060ft high tower has more than six million visitors a year – an average of more than 16,000 a day.
A successful strike on the 7,500 ton iron tower, which was looked down on Paris since 1889, would be a French 9/11 and could cost thousands of lives.
The threat was uncovered in a “vague and muffled” radio conversation picked up by air traffic controllers in Lisbon on Thursday.
It comes after a spate of other threats made in recent days on the websites linked to Osama bin Laden’s Al Qaeda terror network, calling for the “brothers of Islam to strike Paris”.