Iran's state-run television quoted the Islamic Republic's chief nuclear negotiator as saying on Tuesday that Iran has prepared an "updated nuclear proposal" and is ready to hold negotiations with world powers.
"We've seen the reports, though we have not heard anything conclusively from the Iranians on that," White House spokesman Robert Gibbs said.
Gibbs said the United States and its allies still hope Iran will embrace an offer made by six world powers in April to hold talks.
"It's still out there, it is still waiting for a response," Gibbs said.
U.S. President Barack Obama has given Iran until later this month to take up a six-power offer of talks on trade benefits if it shelves nuclear fuel production, or face harsher sanctions.
Gibbs noted that officials from the six world powers meet on Wednesday in Germany to discuss Iran's nuclear program.
"Though we have not seen anything from them, it has always been our hope and goal that the Iranians will live up to their international obligations and give up their nuclear weapons program," Gibbs said.
(Reporting by Steve Holland; Editing by Doina Chiacu)
