US President Barack Obama and German Chancellor Angela Merkel on Thursday underscored the importance of continuing free trade negotiations between the United States and Europe.

Merkel said she was sure that the two countries would return to the stalled trade deal "one day".

She said Germany would do everything to work well with newly elected US President Donald Trump, who has opposed the Transatlantic Trade and Investment Partnership (TTIP).

Obama also addressed Britain's vote exit the European Union, saying he hoped the negotiations would be conducted in a smooth, orderly and transparent fashion.