The officials spoke on condition of anonymity because Solana's office has not yet characterized the document. They said the lack of a clear response means that discussion of new sanctions against Iran could begin as early as Wednesday, when senior diplomats from the six countries that made the offer will speak in a conference call to discuss the way ahead.
The United States and others accuse Iran of trying to develop nuclear weapons under cover of a civilian atomic energy program. Iran denies the charge.
