WASHINGTON (AP) -- Vice President Joe Biden has thanked Switzerland's president for his country's role in tense negotiations over the fate of Americans held in Iran.


Switzerland helped secure the release over the weekend of four Americans whom Iran had detained for years. A Swiss aircraft flew some of them out of the country Sunday.


The Swiss government acts as the "protecting power" for the U.S. in Iran. The United States and Iran do not have formal diplomatic relations.


Biden met with Swiss President Johann Schneider-Ammann after arriving in Zurich on Monday.


The vice president is in Switzerland this week to address the World Economic Forum in the ski resort of Davos, before continuing on to Turkey.


By AP