Iranian Foreign Minister Mohammad Javad Zarif accused Israeli Prime Minister Benjamin Netanyahu of lying in his rejection of Tehran's overtures to the West as a cosmetic "charm offensive".
"We have seen nothing from Netanyahu but lies and actions to deceive and scare, and international public opinion will not let these lies go unanswered," Zarif said in an interview with Iranian television broadcast on Tuesday.
Zarif was speaking from the United Nations, where Netanyahu was set to the address the General Assembly later Tuesday, the same forum where last year he used a cartoon bomb as a prop to underline how close he believed Iran was to producing a nuclear warhead.
"For 22 years, the Zionist regime has been lying by repeating endlessly that Iran will have the atomic bomb in six months," Zarif said.
"After all these years, the world must understand the reality of these lies and not allow them to be repeated."
Netanyahu headed to the United States determined to use his UN address and a White House meeting with President Barack Obama on Monday to expose what he regards as "sweet talk" from Iran about wanting to allay Western concerns about its nuclear programme.
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At the White House meeting, Netanyahu said it was vital that "Iran fully dismantles its military nuclear programme".
He urged Obama to keep US sanctions in place throughout negotiations between Iran and the major powers over its nuclear programme.
Zarif said that "Netanyahu was the most isolated man at the UN" as he prepared to give his General Assembly speech.
Foreign ministry spokeswoman Marzieh Afkham echoed Zarif's comments at a press briefing in Tehran on Tuesday.
"The pressure coming from the Zionist regime is down to its isolation and its anger that the policy of the Iranian government has been well received," Afkham said.
She said Washington now faced a "major test to show if it can stand up to the warmongers."