BEIJING, July 11 (Xinhua) -- The United States and the European Union (EU) have urged Iran to respond to an international nuclear proposal before Saturday's G8 summit, but Iran refused to make a hasty decision on the offer before ambiguities are answered.

    U.S. Secretary of State Condoleezza Rice said on Monday: "It is time to get an authoritative answer."

    "We hope the Iranians chose the path before them for cooperation, but, of course, we can always return to the other path should we need to," Rice said. "And that path ... was, of course, the path to the Security Council."

    Six countries, namely, the United States, Russia, China, France, Britain and Germany offered a package of political and economic incentives to Iran on June 6 in exchange for a pledge to suspend uranium enrichment.

    But Tehran has insisted no precondition shall be attached to the negotiations.

    "I think any reasonable person would say six weeks is quite long enough to consider that," State Department spokesman Sean McCormack said at a briefing earlier.

    "They have had plenty of time. They have had plenty of time at this point to provide an answer to the question that was put before them," McCormack said.

    Leaders of the Group of Eight (G8) major industrial countries are expected to begin their annual meeting in Russia's Saint Petersburg on July 15.

    At the particular timing, the EU also pressed for an early response from Tehran.

    "It's clear that we need the response as soon as possible, and that the time element is very important," said Cristina Gallach, spokeswoman for EU foreign policy chief Javier Solana.

    "We have to exert pressure so that this happens as soon as possible," she insisted.

    But Iran was firm on its stance.

    Iranian President Mahmoud Ahmadinejad has said Iran will make reply to the proposal by Aug. 22, on which the Iranian month of Mordad ends.

    Iranian Foreign Minister Manouchehr Mottaki said on Sunday there were still some questions and ambiguities in the proposal, on which Solana was unable to give answers.

    Solana will meet Tehran's top nuclear negotiator Ali Larijani in Brussels on Tuesday.

    The encounter will be followed by consultations among the foreign ministers of the six countries which have drawn up the package. The Iranians are not expected to participate in the consultations on Wednesday.

    The United States has accused Iran of secretly developing nuclear weapons under a civilian front, but Iran has said its nuclear program is for peaceful purpose.

    Iran resumed uranium enrichment-related activities in January. As a result, the EU suspended talks and sought to bring the issue before the UN Security Council.

    The six-nation proposal put forward to defuse the nuclear crisis includes a state-of-the-art nuclear reactor with a guaranteed fuel supply, economic benefits and other incentives if Iran halts uranium enrichment. Enditem