The Bush administration moved today to cement international support for new U.N. sanctions on Iran over its nuclear programs and rebuked President Ahmadinejad of Iran for declaring the issue “closed.”

A day after a defiant Mr. Ahmadinejad told the U.N. General Assembly that his country would defy further U.N. Security Council efforts to impose additional penalties, Secretary of State Rice and her top aides sought to marshal consensus on the move.

“I am sorry to tell President Ahmadinejad that the case is not closed,” the State Department’s no. 3 diplomat, Nicholas Burns, said. He was to meet with senior diplomats from the five permanent Security Council members and Germany to craft elements of a new sanctions resolution.

“We’re going to keep going,” Mr. Burns told reporters. “If Mr. Ahmadinejad thinks somehow that he has been given a pass, he is mistaken about that.”

Mr. Burns’s talks over dinner with diplomats from Russia, China, Britain, France, and Germany will set the stage for a second meeting tomorrow and then one between Ms. Rice and the group’s other foreign ministers on Friday when the resolution is expected to be further defined.

However, he said it is unlikely that the text of a new resolution will be agreed to this week.

As Mr. Burns spoke, Ms. Rice was assuring Iran’s wary neighbors in the Persian Gulf of American backing to improve their defenses against a “hegemonistic Iran” through proposed multibillion dollar arms sales, a senior State Department official told reporters.

In a meeting with the foreign ministers of the six-member Gulf Cooperation Council — Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, and the United Arab Emirates — along with Egypt and Jordan, Ms. Rice heard deep fears about Iranian attempts to dominate the region, the official said.

The official, speaking on condition of anonymity to discuss a private diplomatic exchange, said all eight countries told Ms. Rice that “they are not going to surrender to Iranian hegemony.”

The Bush administration is in discussions with the Saudis and its other allies in the Gulf to prepare arms sales packages worth about $20 billion despite concern from some in Congress that they could destabilize the region and hurt Israeli security interests.

The senior State Department official said specific details of the proposed sales were not discussed today but that Ms. Rice told the Gulf ministers they could count on solid American support.

America accuses Iran of trying to develop nuclear weapons, something Tehran adamantly denies, and has been encouraged in recent months by stronger statements on the matter from Security Council members, notably France.

Iran is already subject to two U.N. sanctions resolutions as well as a growing number of financial penalties from individual nations but China and Russia have been reluctant to agree to a new U.N. resolution.

Among ideas being considered for the new resolution are widening existing financial sanctions on Iranian entities and possible diplomatic measures, officials said.

The Bush administration is considering wide-ranging sanctions against the Iranian Revolutionary Guard Corps’ Quds force, which is accused of supporting insurgents in Iraq, by naming it an international terrorist group.

The Senate today voted 76-22 in favor of a resolution urging the State Department to designate the corps a terrorist organization.

While the proposal, by Senators Lieberman and Kyl, attracted overwhelming bipartisan support, a small group of Democrats said they feared labeling the state-sponsored organization a terrorist group could be interpreted as a congressional authorization of military force in Iran.

Mr. Ahmadinejad told world leaders yesterday his country would defy attempts to impose new sanctions by “arrogant powers” seeking to curb its nuclear program, accusing them of lying and imposing illegal penalties on his country.

He said the nuclear issue was now “closed” as a political issue and Iran would pursue the monitoring of its nuclear program “through its appropriate legal path,” the International Atomic Energy Agency, which is the U.N.’s nuclear watchdog.