German Chancellor Angela Merkel will miss the opening of the G20 summit in Argentina after her plane was forced to land shortly after leaving Berlin.
The plane carrying Mrs Merkel's team turned back while flying over the Netherlands, because of a communications failure.
The Airbus made a safe but unscheduled landing in Cologne, according to BBC.
Mrs Merkel flew to Madrid on Friday before taking a scheduled Iberia airlines flight to Buenos Aires.
The captain announced to passengers on Thursday evening that he had decided to turn back after the "malfunction of several electronic systems".
The plane's communications system went down and the crew had to use a satellite phone to contact air traffic controllers, Germany's Spiegel website reported.
The problem is thought to have been with an electronic distribution box, which controls both the radio and discharge of aviation fuel.
The German air force denied suggestions that the plane's electronics could have been sabotaged. "There's is absolutely no indication of a criminal background," a spokesman said.
An added problem for the plane was that Cologne airport's longer runway was unavailable, Spiegel added.
As the A340 had to slow down quickly and it was still fully laden with fuel, its braking system overheated and the fire brigade met the plane on the tarmac.
The German delegation was kept on the plane for some time before officials decided to travel by bus to a hotel in Bonn.