The Washington Monument will be closed until repairs are made to its troubled elevator. (Carolyn Kaster/AP)

The Washington Monument will be closed indefinitely because of ongoing problems with its elevator.

Officials with the National Park Service made the announcement Monday, saying that the elevator has “ongoing reliability issues” and that they are not able to determine the cause of the problems.

“As a result, we have made the difficult decision not to reopen the Washington Monument until we can modernize the elevator control system,” according to the Park Service announcement.

Officials didn’t specify how long the monument will be closed but said that more information will be released in the next couple of weeks.

The National Park Service announced on Sept. 26 that The Washington Monument is closing indefinitely because of ongoing problems with its elevator. The monument will remain closed until its elevator control system can be modernized, a process expected to take up to nine months once work begins. (WUSA)

In an email, Mike Litterst, a spokesman for the National Park Service, which oversees the monument, said “it’s a long-term closure, one that will be measured in months.”

The monument has been closed repeatedly during the past few months.

The 555-foot-tall marble-and-granite monument was damaged in a 2011 earthquake and was repaired, although its elevator had long been plagued with troubles before the earthquake.

When the 5.8-magnitude earthquake hit the area, the monument sustained cracks, and some pieces of mortar and stone became loose. In some cases, stones became so loose from the monument’s structure that large cracks opened and light shined through.

After the earthquake, the monument underwent extensive repairs that cost about $15 million and involved 500 tons of scaffolding. The repairs were funded by the government and a $7.5 million donation from local businessman and philanthropist David M. Rubenstein.

The monument reopened in 2014, but its elevator has remained problematic.

The Park Service said there have been varied reasons for the elevator troubles. One of the biggest issues is that the elevator is 15 years old and has mechanical and electrical systems that are nearly worn out, officials have said.

Also, some of the damage from the quake on Aug. 23, 2011, is just now being discovered. Litterst said moisture might have gotten into cracks and into mechanical areas.

On a few occasions, visitors have been stranded as they rode the elevator. The life expectancy for elevators is between 15 and 20 years, depending on usage.

The monument’s elevator runs from 9 a.m. to 5 p.m. year-round, and later during the summer. The monument’s steps have been closed to visitors, except in case of emergencies, since the 1970s.

This summer, Litterst described having to close the monument as a “horrible inconvenience and frustrating for us and our visitors.”

The monument receives about 600,000 visitors a year and is considered one of the tallest free-standing masonry structures in the world. Its original construction started in 1848 and was done in 1884.