The White House said today it was heartening that Iran is taking an incentives package from six world powers seriously, but said that the Iranian government needed to suspend nuclear enrichment activities.
Iran's chief nuclear negotiator Ali Larijani described the package as positive but containing ambiguities after being presented with it by European Union foreign policy chief Javier Solana.
Mr Solana has been briefing the Iranian government on a package of economic and political incentives agreed on Friday by the five permanent UN Security Council members and Germany.
There is also the implicit threat of UN sanctions if Iran fails to agree.