(VOVworld) - Iran is "forever" banned from building nuclear weapons under an existing international treaty, top US diplomat John Kerry said Wednesday, seeking to dismiss fears that limits on its program imposed in a new deal may eventually be lifted. He reiterated that there would be no reduction in restrictions at any time that permits Iran to build a nuclear weapon," Kerry told US lawmakers when pressed on whether a deal with Tehran would eventually allow them to develop atomic arms.

U.S. Secretary of State John Kerry testifies before the House Appropriations Committee's State, Foreign Operations and Related Programs Subcommittee, in Washington, February 25, 2015. AFP/Chip Somodevilla

The world powers -- Britain, China, France, Germany, Russia and the United States – are speeding up negotiations to reach a deal with Iran regarding Teheran’s controversial program. The aim is to construct a deal, which through limiting enrichment and destroying centrifuges for example, would ensure that it would take the Islamic Republic at least a year to gather together enough fissile material to build a bomb. That would give the international community ample time to ward off the threat.