Pressure is mounting on Iran to respond positively to the offer, with Western nations threatening to reactivate efforts to punish it through possible U.N. Security Council sanctions unless it suspends uranium enrichment and agrees to talks on its nuclear program by July 12.
On Wednesday, senior EU envoy Javier Solana will tell top Iranian nuclear negotiator Ali Larijani that Iran must accept the terms of the package by July 12, when foreign ministers of the five permanent Security Council nations and Germany consult in Paris, diplomats said.
Russia and China have opposed sanctions against Iran, a major commercial partner for both countries.
But Western nations are pushing Moscow and Beijing to support them on U.N. Security Council action if Tehran refuses the package of incentives meant to wean it off enrichment, the AP reports.
Iranian officials have said they would not respond to the six-power offer before mid-August, a gambit described by one of the diplomats as an attempt to stall beyond the July 15-17 summit of the Group of Eight industrialized nations in Russia.
The enrichment program can produce fuel for nuclear power plants or material for atomic bombs.