'We also both agree that if Iran does not respond to serious negotiations and resolve this issue in a way that assures the international community that it's meeting its commitments, and is not developing nuclear weapons, then we will have to take additional actions, and serious additional sanctions remain a possibility,' the US president added.

Iran has been under international pressure to halt uranium enrichment, used in both electricity generation and weapons production. Tehran has repeatedly rejected the demand, insisting it is pursuing a purely civilian programme. Several Western powers have called for harsher sanctions against Tehran if it does not agree to halt uranium enrichment.

Meanwhile, Iran has agreed to discuss its nuclear programme with Russia, the US, China, Britain, France and Germany Oct 1.

--RIA Novosti

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