German Chancellor Angela Merkel touched down more than two hours late in New Delhi for the start of her visit to India, after Iran refused to allow her plane access to its airspace.
The plane was forced to turn round and circle over Turkey before permission was finally granted - just before the plane ran out of fuel.
German Foreign Minister Guido Westerwelle requested the presence of the Iranian ambassador in Berlin on Tuesday. He said he wanted to make it clear that such a "breach of international protocol would not be tolerated."
"It is absolutely unacceptable that Iran should hold up the German chancellor's journey," said Westerwelle. "It shows a lack of respect for Germany that we will not tolerate."
Merkel is leading a large delegation of ministers and businessmen to India, seeking improved trade with booming South Asian economies. She is meeting Prime Minister Manmohan Singh and President Pratibha Patil in the Indian capital on Tuesday, before continuing her tour in Singapore.
It is unclear why Iran suddenly withdrew permission to enter its airspace in the early hours of Tuesday morning.
On Monday evening, when the plane took off from Berlin, the German authorities said they had already been given the green light to fly over Iran. However, the Iranians have disputed this.
A second German plane carrying four German government ministers flew over Iran without a problem and landed on time in New Delhi.
"There's no precedent for this," said government spokesman Steffen Seibert. "An unusual start to the India trip," he added on Twitter. He called it a violation of diplomatic privilege that Merkel had never experienced before.
Only after an hour of negotiations, with Turkey as mediator, did Tehran grant the chancellor's plane permission to fly over Iran. If the dispute had gone on any longer, the Airbus 340 would have been forced to make a stopover in Turkey for refueling.
This was also the maiden flight of the chancellor's new plane, the "Konrad Adenauer," named after post-war Germany's first chancellor. Officials on board attributed the delay to "coordination problems." The plane was also carrying a large group of industry representatives and journalists.
Seeking improved trade
The main topics on the agenda for the German-Indian talks will be nuclear energy and the nomination of a new head of the International Monetary Fund - two issues which divide the two nations.
The two sides are also hoping for deeper commercial ties.
The German chancellor wants to promote European fighter aircraft. The Eurofighter consortium made up of Germany, the UK, Spain and Italy is hoping to sign a contract with the Indian air force for 126 new planes, worth 7 billion euros ($11 billion).
Germany is India's biggest trading partner in Europe, with bilateral trade at 15.4 billion euros in 2010. Indian officials estimate that this figure will grow to 20 billion euros by 2012.
Author: Joanna Impey (dapd, dpa, Reuters)
Editor: Nicole Goebel