The Eiffel Tower has been closed to visitors after a terror suspect carrying a large rucksack was reportedly spotted scaling the attraction.
A helicopter could be seen circling the 986-foot structure after officials raised the alarm just before 9am local time, according to The Daily Mail.
According to the newspaper, a police source helping evacuate the tower said: "There's been a report of a man with a rucksack."
Hundreds of people queueing to get into the attraction were reportedly turned away, with a police cordon formed around its base.
The tower has frequently been threatened by terrorist groups, including Al Qaeda and ISIS, with security stepped up since attacks by three radical Islamist gunmen in the city in January.
But police said there may be another explanation for Sunday's security breach - the man may have been a parachutist hoping to perform a jump.
