ATHENS, Greece — Workers on the Greek capital’s subway system have walked off the job in a 24-hour strike that has snarled traffic across Athens.

The metro workers’ union called the strike to protest what they say is underfunding of the public transport system, and the possibility that the Athens Metro would be included in privatization plans.

The Athens Metro is the capital’s most popular mode of public transport, serving nearly 1 million passengers per day.

The morning rush-hour saw gridlock on many Athens streets Tuesday as commuters used their cars.