The two-year period for Britain and the European Union to settle the terms of their split after British Prime Minister Theresa May filed divorce papers on Wednesday is very tight, a spokesman for the German Foreign Ministry said.
"The time-frame is damn narrow," Martin Schaefer said at a regular government news conference.
Germany's foreign minister cautioned that negotiations on Britain's exit from the European Union would not be easy for either side and said it was difficult to understand how any country could believe it would be better off alone in the current global environment.
Speaking in Berlin after British Prime Minister Theresa May formally triggered the two-year countdown to Brexit, Sigmar Gabriel also made clear that the unity of the other 27 EU member states would be Germany's highest priority in the talks.
"The negotiations will surely not be easy for either side," he said. "Bad feelings are understandable. For many it is difficult to understand, especially in these turbulent times, how anyone can believe they would be better off alone. But this can't be the basis for defining our future relationship."
Britain has formally triggered the process of leaving the European Union, Prime Minister Theresa May said on Wednesday.
European Council President Donald Tusk received a letter from the British ambassador to the EU on Wednesday. The notification letter, handed over in Tusk's Brussels office in the presence of journalists, triggers a two-year countdown to Brexit under Article 50 of the EU's Lisbon Treaty.
"The Article 50 process is now under way and in accordance with the wishes of the British people, the United Kingdom is leaving the European Union," May told parliament.
May said Britain would seek to agree its future partnership with the bloc alongside the withdrawal terms.