U.S. Secretary of State John Kerry was expected in Geneva to participate in talks between representatives of Iran and leading world powers over Iran's disputed nuclear program.
The foreign ministers of France and Britain also announced Friday they are travelling to Geneva.
The State Department said on November 22 that Kerry "is going to Geneva with the goal of continuing to narrow the differences."
The statement warned that Kerry's trip should not be taken as a sign that a breakthrough is imminent.
Kerry was expected to arrive early on November 23. There is no scheduled deadline for the end of the talks.
Speaking at a briefing in Washington before the announcement, U.S. State Department spokeswoman Jen Psaki said negotiators continue to "narrow the gaps" in the proposed text.
A key sticking point is whether Iran has the "right" to enrich uranium, as Tehran insists. Psaki emphasized the United States and other P5+1 countries do not recognize such a "right."
"We don’t recognize that any country has a right to enrich [uranium]. That's been our policy for decades. Iran has been saying, I believe for decades, that they believe they have the right to enrich," Psaki said. "So what we are working through is whether those two positions can be reconciled through the negotiations and through an agreement. And that’s what we’re hopeful of."
Earlier there were reports from Geneva that an unspecified compromise had been reached on this issue.
The so-called P5+1 -- Britain, China, France, Russia, the United States, and Germany -- are pushing Tehran to freeze parts of its nuclear program, which they suspect is aimed at producing nuclear weapons. In return, they are offering a partial lifting of international sanctions against Iran.
Based on reporting by Reuters, AP, and AFP