WASHINGTON (AFP) - More sanctions against Iran over its nuclear ambitions would destroy painstaking international talks with Teheran, an advisor to US President Barack Obama warned Congress on Monday.

"Congress has played a hugely important role in helping to build our sanctions on Iran, but they shouldn't play the spoiler now. Additional sanctions or restrictive legislation enacted during the negotiation would blow up the talks, divide the international community and cause the United States to be blamed for the failure to reach a deal," said National Security Advisor Susan Rice.