The United States says major world powers will have no choice but to pursue new sanctions against Iran in the absence of a positive reply to their offer of incentives for it to halt uranium enrichment.  The State Department says a written response to the offer is expected Tuesday.  VOA's David Gollust reports from the State Department.

Iran's President Mahmoud Ahmadinejad at the Natanz nuclear facility (2007 photo)

With a two-week deadline for an Iranian reply having passed over the weekend, senior diplomats of the five permanent U.N. Security Council member countries and Germany conferred by telephone and renewed their warning of further sanctions against Iran.

The so-called P Five Plus One offered Iran an enhanced package of incentives in June, including aid for a civil nuclear program, if it dropped a uranium-enrichment project the United States and European allies believe is weapons related.

Iran was non-committal about the offer at a July 19 meeting in Geneva and was given an additional two weeks to respond.

In a talk with reporters, Acting State Department Spokesman Gonzalo Gallegos said Iranian nuclear negotiator Saeed Jalili has told European Union chief diplomat Javier Solana Iran will give a reply in writing on Tuesday.

Gallegos said the major powers are disappointed at the lack of a response thus far, and he made clear that if Tuesday's reply is not positive, Iran can expect more sanctions:

"We remain committed to both tracks of the P Five Plus One dual-track strategy," said Gonzalo Gallegos. "Accordingly, we agreed in the absence of a clear, positive response from Iran that we have no choice but to pursue further measures against Iran as part of this strategy.  Iran has a clear choice: engagement or isolation.  The P Five Plus One incentives package contained everything Iran needed to pursue a modern civil power nuclear program which Iran's leaders claim is their aim."

The U.N. Security Council has already approved three sanctions resolutions against Iran.  The P Five Plus One, in the incentives plan, offered to suspend sanctions, if Iran suspended enrichment and returned to negotiations over the future of its nuclear program.

EU diplomat Solana and Jalili had what a European spokesman described as an inconclusive telephone discussion Monday.

Iran has insisted that its nuclear program is entirely peaceful and that it has a right to pursue an enrichment capability.

Tehran submitted a document to Solana July 19 that is understood to have proposed several rounds of ministerial level negotiations while avoiding any promise to halt enrichment.

U.S. spokesman Gallegos said P Five Plus One political directors will confer by telephone again soon, presumably after submission of the Iranian paper to Solana.

The U.S. political director is Undersecretary of State for Political Affairs William Burns, who attended the July 19 meeting with Jalili, despite the absence of U.S. diplomatic relation with Iran.