Bavarian police say they have arrested two men, an Iraqi and a Nigerian, on suspicion that they may have been preparing a "serious act of violence."

The state criminal police office said the 46-year-old Iraqi and the 29-year-old Nigerian were detained in Munich and nearby Fuerstenfeldbrueck on Thursday following a tip to Bavarian security authorities.

They didn't elaborate but the daily Sueddeutsche Zeitung quoted Munich prosecutor Thomas Steinkraus-Koch as saying there had been indications the two were in contact with members of the Islamic State group.

Police said no suspicious objects have been found and that, as far as authorities knew, there was no "concrete danger to the population."