"Moreover, I believe that the question is not so serious at the moment for the U.N. Security Council or the group of six to consider any introduction of sanctions. Russia stands for further political and diplomatic efforts to settle the issue."

Ivanov is regarded as close to President Vladimir Putin.

The Security Council passed a legally binding resolution on July 31 telling Iran to suspend its nuclear enrichment program within 30 days or risk sanctions.

Iran says it is enriching uranium solely to generate electricity. The West suspects the Iranian nuclear program is a front for building atom bombs.

U.S., French and German leaders said that Iran's 21-page response to the incentives offer was unsatisfactory because it did not specifically agree to stop purifying uranium.

European Union foreign policy chief Javier Solana said on Friday that Tehran's reply had touched on "many different elements, different from the ones that we had proposed."

"For that reason we will have to hold a dialogue session ... or a conversation with the ... Iranians to improve upon some of the expressions and meanings of the subject matter treated in its document," he told Spain's RNE state radio.

But while Washington, backed by closest ally Britain, has said the six powers will move quickly to adopt sanctions if Iran disregards the deadline, Germany and France have been less conclusive in public and Russia and China have been unwilling.

"For the moment, it (the Iranian response) is not satisfactory," French Foreign Minister Philippe Douste-Blazy said on RTL radio, but added it was important to avoid escalating conflict with Iran and the Muslim world.

"The worst thing would be to escalate into a confrontation (between the West and) Iran on the one hand, and the Muslim world with Iran...," he said.