The measures are intended to replace temporary metal barriers and prefabricated buildings that were put in place around the monument in response to the deadly attacks that have hit France since early 2015. Under plans approved by the city council in March, bullet proof glass walls will be built on the two sides of the tower parallel to the river Seine. The other two sides will be protected by metal fences designed in the pattern of the tower's shape.

The security measures, which are expected to cost 20 million euros (23.9 million dollars), should be finished by mid-2018.

The city's tourism chief, Jean-Francois Martins, said the renovations "will not disrupt visitors' arrival in any way" and that tourists would still be able to walk up to the tower for free, after passing through security checks.

A two-year project to repaint the 128-year-old wrought-iron tower will kick off in 2018, as well as refurbishment of its elevators, which will take two years longer. The building of a new reception centre will start in 2021 and last for two years, Martins said. But he indicated that controversial plans for an underground centre with a shopping gallery have been scrapped.

City officials are trying to upgrade the site without denting visitor numbers as Paris prepares to host the 2024 Olympic Games.

The Eiffel Tower was Paris' fourth-most-popular visitor attraction in 2016, with almost 6 million visitors.

French authorities have stepped up security around key tourist sites in response to attacks in Paris, Nice and elsewhere that have killed more than 230 people since early 2015. On several occasions this year, security forces on patrol at such sites have themselves been attacked, with one policeman killed in an attack on the Champs-Elysees in April. Last month a man armed with a knife tried to force his way through a security checkpoint at the Eiffel Tower, but he was quickly overpowered and disarmed. The suspect, arrested at the scene, was remanded to a psychiatric hospital where he had previously been treated.
 

is/at (dpa, afp)