No one was injured, and the damage to the building is limited. The police cordoned off the area, which is centrally located near Syngrou Avenue in a neighborhood with many bars and restaurants.
The explosive device was found, according to the police, in a bag.
Shortly before the blast, a newspaper and a news website received an anonymous bomb threat. The caller claimed that a bomb had been placed outside the train company's premises and would detonate within 40 minutes. The call was made at 20:35 local time, and the explosion occurred at 20:54, according to local media.
The police bomb squad did not have time to defuse the object.
The event takes place simultaneously with ongoing protests in Greece following the severe train crash, the worst in the country's history, outside the city of Larissa in February 2023. 57 people died when a passenger train and a freight train collided head-on.
The popular anger is rooted in criticism of the government's and authorities' handling of the accident.
The government has survived several votes of no confidence in parliament, the latest in March. A trial is also underway with over 40 defendants.
