WASHINGTON — The Federal Transit Administration has ordered Metro to take immediate action to address some of the problems recently discovered during more than 100 inspections of the rail system.

In a scathing letter obtained by The Washington Post, the FTA told Metro General Manager Paul Wiedefeld the problems are so serious that they present “a clear concern for public safety.”

Among other things, inspectors found fire extinguishers that do not work, and emergency walkways blocked by debris.

“These defects create a systematic safety condition that significantly limits WMATA’s ability to manage a fire or smoke emergency in the tunnel,” wrote Thomas Littleton, the FTA’s associate administrator for safety.

The federal agency took control of Metro safety oversight back in October. Since then, the agency has conducted 107 inspections and discovered 229 defects.

“Our folks are still compiling the data and developing recommendations going forward,” U.S. Transportation Secretary Anthony Foxx told WTOP in an interview last week.

In its letter, the FTA also criticized Metro workers, saying they were spotted ignoring safety procedures on a number of occasions. As a result, the federal agency ordered Metro to conduct immediate safety briefings for workers.

Metro spokeswoman Sherri Ly told The Washington Post that the agency has been briefed by FTA officials and that “all safety critical items are receiving priority attention.”