Iran and the United States both denied any deal had been reached for one-on-one nuclear talks, as The New York Times reported -- even though the White House said it was open to such a dialogue.
The Times report on Saturday came at a key point in the US presidential campaign, with incumbent Barack Obama set to face Republican rival Mitt Romney on Monday in their last of three debates, this one focused on foreign policy.
Experts say Iran and its disputed nuclear program will be a top concern for whoever wins the White House following the November 6 vote.
When asked Sunday about The New York Times report, Iranian Foreign Minister Ali Akbar Salehi said: "We are not involved in such a thing right now."
In Washington, White House National Security Council spokesman Tommy Vietor said Saturday: "It's not true that the United States and Iran have agreed to one-on-one talks or any meeting after the American elections."
Vietor also emphasized that Obama has "made clear that he will prevent Iran from getting a nuclear weapon."
The double denial was made even more intriguing when Israeli deputy premier Moshe Yaalon first said he was aware of US attempts to directly negotiate with Iran but did not believe such talks had taken place.
Shortly afterwards, Israeli Prime Minister Benjamin Netanyahu -- who has asked Washington and the international community to set clear 'red lines' on Iran -- said he was unaware of any such "contacts."
"Iran used the talks and negotiations with the Five Powers to drag its feet and to gain time to advance its nuclear weapons program," Netanyahu said.
Israel and Western powers accuse Tehran of seeking to develop a nuclear bomb, though Iran insists their nuclear program is for civilian purposes.
The Jewish state, the Middle East's sole but undeclared nuclear power, has refused to rule out a military strike to prevent Iran from obtaining nuclear weapons.
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Obama has favored a two-pronged approach, combining pressure through sanctions with diplomatic negotiations, a strategy his supporters say is working. He has always said the door was open for negotiations.
On Saturday, Vietor reiterated that the United States has "said from the outset that we would be prepared to meet bilaterally."
Washington will continue to work alongside global powers on a "diplomatic solution" to the nuclear standoff with Tehran, Vietor said.
Iran's Salehi conveyed a similar message, confirming that talks between his country and the so-called P5+1 global powers -- Britain, China, France, Germany, Russia and the United States -- would resume next month after the US election.
Russia said last week that a new round of talks between Iran's chief negotiator and six-nation representative Catherine Ashton, the European Union's foreign policy chief, could take place in November.
The talks had been stalled, with tough sanctions aimed at forcing a breakthrough.
When Obama took office, "the United States was isolated from the rest of the world on Iran," his former chief-of-staff and current Chicago mayor Rahm Emanuel told ABC News on Sunday, the eve of the foreign policy debate.
"Three and a half years later, the tables have been turned. Iran is isolated from the rest of the world," thanks to Obama's leadership, he said.
But Republicans again accused the president of being weak on the issue.
"As we talk with the Iranians, whether it is bilaterally or unilaterally, they continue to enrich" uranium, Republican Senator Lindsey Graham said on Fox News.
"I think the time for talking is over," he emphasized.