PARIS – The Eiffel Tower's elevators ground to a halt on Tuesday as an industrial dispute over security and working conditions brought workers at the Paris monument out on strike.

Thousands of visitors hoping for breathtaking views of the city's skyline were left grounded as many of the Tower's 300 staff walked out over late-running maintenance work and pay disputes.

Union representatives said they have been complaining about mismanagment of repairs to the 324-metre wrought iron structure for years.

Renovation of the west lift was projected to last 18 months when work began in 2008 but the project remains unfinished and employees say the facilities are insufficient to welcome the daily flood of up to 30,000 visitors.

"It took them two years to build (the Eiffel Tower), and now it's taking more than five years for one lift," said one disgruntled employee, who declined to be quoted by name.

Staff say overcrowding poses a risk to security and undermines their working conditions.

Visitors were unhappy they had not been warned.

"It's disappointing spending this much money to come here and you can't come to the one landmark people probably come here to see most," U.S. tourist Jamie McNulty said.

Built for the Universal Exhibition in 1889, the Tower was meant to last 20 years but has since become a symbol of the city. It welcomes almost seven million visitors a year, according to its website, which operators say makes it the most-visited paid-for monument in the world.