The severe disruption of the German train network on Saturday was a result of "sabotage" targeting communications equipment, according to operator Deutsche Bahn, although the government said no motives were detected.

"Cable sabotage" was the cause of the breakdown, which led to a three-hour suspension of train services throughout northern Germany, a spokesperson for the company told AFP.

According to German Transport Minister Volker Wissing, vital cables were "deliberately and intentionally damaged" in two locations. "It is clear that this was a targeted and deliberate action," he stated, adding that the cause was not "yet known". He called the incident "clearly premeditated".

There was specifically damage to the GSM-R, a radio network used for communication on the railway, according to security authorities.

Any damage to the cable would require "certain knowledge" of the rail system, the Bild daily revealed, adding that federal police were investigating. 

Traffic was completely interrupted for about three hours because of "a breakdown in the digital radio system for the trains," before being restored, according to Deutsche Bahn. 

Services between Berlin and territories in the country's west and north, including Schleswig-Holstein, the cities of Hamburg and Bremen, as well as Lower Saxony and parts of North Rhine-Westphalia, were disrupted.

Protection of critical infrastructure 

The Berlin-Amsterdam route was also halted, leaving thousands of passengers stuck at stations throughout the affected areas.

Despite the restoration of rail services, Deutsche Bahn cautioned that cancellations and delays were still possible on Saturday.

The attack comes just over two weeks after sabotage attacks on Russia-Germany gas pipelines Nord Stream 1 and 2.

The German government has likewise increased security for vital infrastructure. Deutsche Bahn is frequently chastised for service delays.

The business announced substantial upgrading plans in early September, including the replacement of 137,000 concrete sleepers. An independent investigation found "production flaws" in the sleepers.

The early June accident of a train in the Bavarian Alps, which killed five people and injured more than 40, highlighted the plight of German rail infrastructure, which has been plagued by years of underinvestment.

The government has been pushing car-loving Germans to take the railway in recent months by offering inexpensive tickets.