President Mahmoud Ahmadinejad of Iran has denounced what's reported to be a secret Iranian document revealing that Teheran plans to test a trigger for a nuclear bomb.
In an interview with ABC News, Mr Ahmadinejad dismissed a document published by The Times newspaper last week as a fabrication from the United States government.
The interview by the American TV network was filmed on Friday and broadcast on Monday.
Mr Ahmadinejad said the report was "fundamentally not true". He said criticism of Iran's nuclear programme had become "a repetitive and tasteless joke".
Iran denies claims it wants to build atomic weapons, saying its nuclear programme is for civilian purposes.
The Times reported last week that it had obtained a document, dating from 2007, describing a four-year plan by Iran to test a nuclear trigger using uranium deuteride.
The BBC reports Iran is already subject to three sets of UN sanctions for its refusal to suspend its uranium enrichment programme.
It is at risk of further sanctions after it rejected a deal to send low-enriched uranium abroad to be refined into fuel for a research reactor.
However, Mr Ahmadinejad said Iran would welcome talks "under fair conditions".