"Following the murder of a 28-year-old man, two suspects were arrested... They are American servicemen", police in the western city of Treves said in a statement.

The death occurred when an altercation broke out between several people at a funfair in the small town of Wittlich, in the state of Rhineland-Palatinate between Treves and Koblenz, on Saturday night.

During the fight the victim "was stabbed to death", and "four people, two men and two women, ran away from the scene of the crime", police said, citing witnesses.

Two members of the fleeing group were quickly identified, as a 25- and 26-year-old whom police arrested before handing them over to US authorities, who will take charge of the case "in accordance with NATO statutes", the police added.

"We've never experienced anything like this here", said Wittlich mayor Joachim Rodenkirch when interviewed by the local press.

The United States has had troops stationed in Germany since World War II, but their numbers have declined since the fall of the Berlin Wall from around 200,000 soldiers in 1990 to 34,500 today.