Sweden's Social Democrat leader was meeting officials from the five Nordic countries and the three Baltic states at a Nordic-Baltic summit in Stockholm.
The Prime Minister introduced Danish Prime Minister Helle Thorning-Schmidt, before falling silent, fumbling with his notes and then saying in English "I have received the wrong papers".
After speaking with a press officer he recovered his composure and presented Estonia's Foreign Trade Minister Anne Sulling and the other international attendees.
Stefan Löfven, a former welder, had no previous experience in local or national government before he was appointed as Prime Minister following September's general election in Sweden.
During the Nordic-Baltic summit, politicians discussed Russia's growing military presence in the Baltic and Sweden's controversial decision to recognize Palestine as a state