German Chancellor Angela Merkel will miss the opening of the G20 summit in Argentina after what she called a "serious malfunction" forced her government plane to make an unscheduled but safe landing.
Merkel and German Finance Minister Olaf Scholz will resume their travel to Buenos Aires early on Friday, but the long flight time means they will arrive after world leaders start their discussions.
The government's Airbus A340 aircraft carrying Merkel and her delegation to the Group of 20 summit of industrialised nations turned around after technical problems surfaced an hour into the 15-hour flight, and landed safely at the Cologne-Bonn airport.
"It was a serious malfunction," Merkel told reporters hours later, after the delegation was brought to a hotel in Bonn. "Luckily, we had an excellent crew and the most experienced pilot of the special air mission wing."
The airplane captain told passengers he had decided to land after the "malfunction of several electronic systems", but said there had been no security risk.
Merkel and other passengers initially remained on board the aircraft, called "Konrad Adenauer", as mechanics inspected its brakes and several fire engines waited nearby, according to a Reuters reporter on board.
Der Spiegel magazine said the entire communication system malfunctioned, constituting a serious emergency, with the crew forced to plan the landing using an on-board satellite phone.
Defence Minister Ursula von der Leyen was informed about the incident immediately, and tried for hours to organise an alternate aircraft to carry Merkel and her entourage.
The German military blog Augengeradeaus reported that the plane's transponder was transmitting the code 7600 which refers to a radio malfunction.
Later, the delegation travelled by bus to a hotel in Bonn. Delegation sources said a different government plane would fly Merkel and Scholz to Madrid, where they would switch to a commercial carrier for the final leg of the trip.
The delay will complicate Merkel's schedule at a meeting where the G20 members expect to face difficult negotiations on myriad issues.
Merkel, who had planned bilateral meetings with the presidents of the United States, China, Russia and India, was unlikely to arrive in Buenos Aires until Friday evening, German government sources said. It was not immediately clear which bilateral meetings would have to be rescheduled.
Scholz was grounded on the same A340 aircraft last month after an International Monetary Fund meeting in Indonesia, according to German media reports. They said the issue involved damage caused by rodents.