A small explosive device has been detonated at the Post Hotel Morosani near Davos as world leaders gather for the World Economic Forum (WEF).
No injuries are reported following the incident, which occurred 1.5 miles away from the official venue for the event at approximately 08:00 GMT this morning.
Swiss police have launched an investigation, which shattered windows in the storeroom of the hotel.
Enquiries are focusing on anti-WEF seeking to disrupt the annual event.
Some 2,500 world political, business and social leaders are in attendance.
Many were expected to attend a lunch entitled Criminals Without Borders, which was scheduled to take place at the hotel at noon.
Speakers including Colombian president Juan Manuel Santos and Robert Wainwright, director of Europol, were due to address the audience.
“A small explosion took place in the basement,” Swiss prosecutors said in a statement.
“Nobody was injured. At no time were the hotel’s guests in any danger.
“The blast did, however, cause some minor damage, including a few broken windows.”