Iranian President Mahmoud Ahmadinejad says Tehran will reject any offer by European envoys that requires an end to Iran's nuclear activities.
The Iranian president said on state television Sunday that any such offer would be invalid.
British, French and German negotiators are drawing up incentives to offer Tehran in exchange for a guarantee that Iran will suspend uranium enrichment.
If Tehran rejects the offer, the United States and the Europeans say they will press for a U.N. Security Council resolution that threatens possible sanctions. Russia and China have threatened to veto any sanctions resolution.
E.U. foreign ministers meet Monday in Brussels to discuss an incentives package that would also offer penalties for non-compliance. The five permanent Security Council members plus Germany are to meet in London May 19th to consider the package.
The Europeans and the United States suspect Tehran is using its nuclear program as a cover for developing an atomic bomb. Iran insists its nuclear intentions are peaceful.
Some information for this report was provided by AFP, AP and Reuters.