U.S. Secretary of State John Kerry will travel to Vienna, Austria, on June 26 to take part in international talks on Iran's nuclear program.
State Department spokesman John Kirby made the announcement in a statement on June 24.
Iran and six world powers -- Britain, China, France, Germany, Russia, and the United States -- are negotiating a deal under which Tehran would curb its nuclear program in exchange for sanctions relief.
The sides have set a June 30 deadline for an agreement.
On June 23, Iranian Supreme Leader Ayatollah Ali Khamenei hardened his stance in the negotiations, saying he rejected a long-term freeze on nuclear research and wanted to ban international inspectors from accessing military sites.
The six powers want limits on Tehran's programs that could have a military use. Tehran denies it is pursuing such weapons.