A departure board at the main train station in Dresden, eastern Germany, shows delays in traffic caused by the arson attack | Arno Burgi/AFP via Getty Images Arson attacks on German railways spark security fears ahead of G20 summit There have been 12 seemingly coordinated incidents nationwide on railroad tracks, police said.

Rail traffic in parts of Germany was disrupted after seemingly coordinated arson attacks early Monday morning on segments of track, sparking security fears in the run-up to the G20 summit in Hamburg next month.

Police in the Saxony region of Germany said there were 12 incidents of arson nationwide between 1 a.m. and 4:30 a.m. Monday on railroad tracks of national rail operator Deutsche Bahn.

The statement said the police found fire in trackside cabling at each of the incidents and believe they were part of a coordinated plan. German media cited security fears connected to the upcoming G20 meeting.

The Operational Center of Defense confirmed that a letter claiming responsibility was posted online Monday morning, hinting the attack may have been carried out by left-wing extremists.

An official at Deutsche Bahn said disruption was ongoing in the Leipzig area and on the track between Lübeck and Hamburg. Commuter services on Berlin’s S-Bahn metro system also were disrupted and a spokesperson could not confirm when the problem would be resolved. Trains on the Cologne-Dortmund route were also disrupted, Deutsche Bahn said, and no services were running on the stretch from Dresden to the Czech border — a tight stretch of track frequently used by freight and passenger traffic.

The attacks occurred three weeks ahead of the G20 meeting during which world leaders will meet in Hamburg for a two-day summit. The Saxony police said a link with the G20 summit could "not be ruled out."

The Operational Center of Defense, which is based in Saxony and handles cases of extremism, is now investigating the incidents in cooperation with Germany's Federal Criminal Police Office.

The incident comes a month after Deutsche Bahn was hit by a global malware attack that disrupted departure boards across the country.

This article was updated with an additional statement from the Operational Center of Defense.