Please turn on JavaScript. Media requires JavaScript to play. Iran concealed a partially-built second uranium enrichment plant in defiance of calls for transparency over its nuclear plans, US President Barack Obama says. The US, UK and France said the UN had to be given immediate access and urged tough new sanctions, while Russia also said it was "seriously concerned". But Iranian President Mahmoud Ahmadinejad denied that the facility was in breach of IAEA rules. The Western leaders would regret their statements, he added. Iran told the UN about the plant on Monday, saying it was not operational yet and would provide nuclear energy. Tehran has previously acknowledged it has one enrichment plant, at Natanz. Iran must abandon any military ambitions for its nuclear programme

Gordon Brown

UK Prime Minister

Full text:Leaders' comments Israel restrained but determined Send us your comments Iran's decision to build a secret facility represented a "direct challenge to the basic compact" of the global non-proliferation regime, US President Barack Obama said, making a statement in Pittsburgh, where he is hosting a G20 summit. Despite Iran's assertions that the facility was for peaceful purposes, the new plant was "not consistent" with that goal, the US president said. 'Line in the sand' Speaking alongside UK Prime Minister Gordon Brown and French President Nicolas Sarkozy, Mr Obama said it was time for Iran to begin meeting its international commitments. ANALYSIS BBC World Affairs correspondent Paul Reynolds Iranian ambitions for this site are not known. It could be that they wanted a back-up in case their main plant