“We will not be proceeding today,” she told AFP.

According to tweets by German journalists on board the Airbus A340, named Konrad Adenauer after Germany’s first post-war chancellor, Merkel will leave for Madrid on Friday and head on a commercial flight for Buenos Aires with a slimmed down delegation.

The Chancellery did not confirm these reports.

A senior journalist with the public national television ZDF said Merkel would spend Thursday night in Bonn.

The plane turned back from the Netherlands and landed in Cologne because it was the only base with a replacement aircraft, the DPA news agency said.

It was met on the tarmac by fire engines, DPA said, adding that the captain told the passengers the plane would have to turn back as a technical problem was disrupting several electrical systems.