Suspected attacks on northern Italy's railway network have led to severe travel disruption in the region, the authorities say, as thousands gathered for the start of the Winter Olympic Games.

Police reported three separate incidents involving damage to railway lines that they believe are connected to the Games.

A fire hit rail infrastructure between Bologna and Venice, triggering delays of up to two-and-a-half hours, and police later found severed cables and an explosive device in locations nearby.

The Ministry of Transport called the incidents an act of "serious sabotage", which they said mirrored vandalism during the Paris Olympics in 2024.

Police said a track switch was set alight near Pesaro, on the Adriatic coast. Several hours later, police discovered severed electric cables near Bologna, along with a rudimentary explosive device left by a track nearby.

Bologna's rail station is a major transport hub, linking cities in the north and south, and east to west lines.

"These actions of unprecedented seriousness do not in any way tarnish Italy's image in the world, an image that the Games will make even more compelling and positive," said Deputy Prime Minister and Transport Minister Matteo Salvini.

A police spokesperson earlier said that they were investigating the incidents and that no one had claimed responsibility.

Salvini compared the events to the Paris Summer Olympics, when saboteurs damaged France's high speed rail network.

"There are similarities in action and timing to the French incident," he told AFP.

Bologna's high speed, state-owned railway had to temporarily close, but traffic was returning to normal by Saturday afternoon.

The opening ceremony of the Games took place on Friday evening in Milan, in Cortina in northeastern Italy and two other locations. Milan and Cortina are both reachable by train from Venice.

Events are spread over hundreds of miles of northern Italy, in locations including the Alps and Dolomite mountains.