A letter from Iran to world powers does not mention the idea of freezing Tehran's nuclear work, an Iranian official said on Tuesday - a step the West demanded to avert more UN sanctions.
Six world powers have offered to refrain from steps to impose more UN sanctions if Iran freezes expansion of its nuclear work. The offer was an initial step in getting talks going on a broader resolution to the stand-off.
The West fears Iran is seeking to build nuclear warheads, a charge Tehran denies.
A European Union official said the letter had not yet been received.
"The letter handed over is not an answer to the offered package (by world powers) ... The letter does not mention the freeze-for-freeze issue," the senior official told Reuters.
'Ready to start formal talks'
The official also said a freeze was not mentioned in telephone talks on Monday between Iran's chief nuclear negotiator Saeed Jalili and European Union foreign policy chief Javier Solana, who is representing world powers.
"During the call, Jalili expressed his readiness to start formal talks (on the incentives package)," the official added.
The freeze idea is aimed at getting preliminary discussions going before starting full negotiations on a package of nuclear, trade and other incentives. But those formal talks will not begin until Iran suspends uranium enrichment.
Enrichment is the part of Iran's program that most worries the West because it can have both civilian and military uses.
Iran, the world's fourth largest oil producer, insists it is only seeking to master technology to make electricity, and has repeatedly refused to halt its atomic work.
The six world powers are Britain, France, Germany, China, Russia and the United States.