John Kerry

Senior Iranian official: progress slow at nuclear talks

But a senior Iranian official warned that negotiations are hampered by differences not only between Tehran and the six other countries it is bargaining with but internally among the six as well.

Kerry was the first to arrive Friday evening, with diplomats from Iran, Britain, Germany, Russia, France and China expected in the Austrian capital over the coming days.

Kerry to rejoin Iran nuke talks in Vienna

The State Department said in a one-sentence statement on Wednesday that Kerry would leave for the Austrian capital on Friday. It will be his first overseas trip since breaking his leg in a bicycle accident earlier this month after a meeting with Iranian Foreign Minister Mohammad Javad Zarif in Geneva.

Diplomats from the United States, the other four permanent members of the U.N. Security Council and Germany have been in intense discussions with Iranian officials in Vienna as the end-of-month deadline for a deal looms.