The United States said Thursday it will make an "expedited" push for economic sanctions against Iran if it does not respond positively by the end of the month to the U.N. Security Council demand that it end uranium enrichment. Iran said earlier this week it is ready for serious talks on the issue but will not stop enrichment as a precondition.

The Bush administration is serving notice on Iran that it can expect an early sanctions move if it does not comply with the Security Council resolution, and that it has already begun consultations in case Tehran defies the August 31 U.N. deadline.

Iran's Foreign Minister Manouchehr Mottaki

Iran gave its formal reply Tuesday to an overture by the five permanent Security Council member countries and Germany for it to suspend enrichment and other sensitive nuclear activities in exchange for economic and political incentives.

In a voluminous response that included requests for clarifications, Iran said it was ready for negotiations on the matter but would not cease enrichment as a precondition.

In a talk with reporters, State Department Acting Spokesman Gonzalo Gallegos reiterated Wednesday's initial U.S. statement that the administration viewed the Iranian reply as serious but that it fell short of what was being demanded by the major powers.

Gallegos said the United States remains committed to a diplomatic solution to the issue and that there is still time, before the August 31 deadline, for Iran to comply:

"We obviously encourage Iran to make the right choice," said Gonzalo Gallegos. "We're seeking the diplomatic solution, trying to make diplomacy work. If Iran does not comply, the resolution makes quite clear that the U.N. Security Council will then adopt appropriate measures under Art. 41 Chapter 7 providing for sanctions, and we're working with the UN Security Council to do this in an expedited manner."

Iran's equivocal answer to the so-called "carrots and sticks" offer is widely seen by U.S. and other analysts as an effort to slow the drive for sanctions, and break up the international consensus against it reflected in last month's U.N. resolution.

Spokesman Gallegos said Secretary of State Condoleezza Rice, in an apparent bid to maintain unity on the issue, spoke by telephone Thursday with Russian Foreign Minister Sergei Lavrov, German Foreign Minister Frank-Walter Steinmeier, and European Union chief diplomat Javier Solana, who has coordinated European dialogue with the Iranians.

The White House said earlier the Iran nuclear issue also figured in conversations President Bush had with German Chancellor Angela Merkel and Italian Prime Minister Romano Prodi.

U.S. officials have said that sanctions, if they prove necessary, would initially include visa restrictions and asset freezes targeted at the Iranian leadership.

Russia and China, though they were parties to the "carrots and sticks" initiative and last month's U.N. resolution that reinforced it, have been cool to the idea of sanctions.

Officials here have said any follow-on penalties might have to be imposed outside the U.N. framework by what they have described as like-minded nations, presumably the United States and European and Asian allies.

Iran, which maintains its nuclear program is entirely peaceful, has said it is entitled to enrich uranium as a signatory of the nuclear Non-Proliferation Treaty. The United States and some European governments believe Iran has a secret nuclear weapons program and is violating its international obligations.