QUITO, Ecuador - Secretary of State Hillary Rodham Clinton on Tuesday called the proposed new U.N. sanctions against Iran's suspect nuclear program the toughest ever, a day before the Security Council was expected to vote on the measure.

Clinton told reporters in Ecuador's capital that there was strong support for a fourth resolution penalizing Iran for its refusal to prove its nuclear program was peaceful and defying international demands to halt uranium enrichment.

"I think it is fair [to say] that these are the most significant sanctions that Iran has ever faced," Clinton said at a news conference with Ecuador's president. "The amount of unity that has been engendered by the international community is very significant."

She declined to predict the outcome of the vote in the 15-member Security Council, but Defense Secretary Robert M. Gates in London said the measure would pass and pave the way for tougher additional measures by the United States and its allies.

"The strategy here is a combination of diplomacy and pressure to persuade the Iranians that they are headed in the wrong direction in terms of their own security, that they will undermine their security by pursuit of nuclear weapons, not enhance it," Gates said.

In the final version of the U.N. resolution, sanctions would be tougher than previous penalties but still far short of crippling economic punishments or an oil embargo.

The sanctions would ban Iran from pursuing "any activity related to ballistic missiles capable of delivering nuclear weapons," bar Iranian investment in activities such as uranium mining, and prohibit Iran from buying several categories of heavy weapons including attack helicopters and missiles.

Annexes to the resolution, agreed to Tuesday, would target 40 new Iranian companies or organizations, including 15 linked to Iran's powerful Revolutionary Guard.

One person was added to the previous list of 40 Iranians subject to an asset freeze, Javad Rahiqi, who heads the Atomic Energy Organization of Iran's Esfahan Nuclear Technology Center.

The sanctions list also includes 22 companies or organizations involved in nuclear or ballistic-missile activities and three entities linked to the Islamic Republic of Iran Shipping Lines. If the resolution is approved, the number of entities under sanctions would more than double from 35 at present to 75.

In New York, Mexico's U.N. ambassador, Claude Heller, the current council president, said that the Security Council vote would take place at 10 a.m. Wednesday.

The Security Council held a private meeting Tuesday afternoon on Iran to meet some of the concerns of Brazil and Turkey, which had called for an open "political debate" on the broader Iranian nuclear issue first.

Neither Brazil nor Turkey is one of the five veto-holding permanent members of the council, although both are currently nonpermanent members of the 15-member body. They recently announced a fuel-swap agreement with Iran aimed at addressing concerns that it may be enriching uranium for nuclear weapons.

After Tuesday afternoon's council meeting, U.S. Ambassador Susan Rice predicted the resolution would be adopted by "a strong majority."

"It is a strong, broad-based resolution that will impose meaningful and significant new sanctions on Iran," she said. "Our aim remains to persuade Iran to halt its nuclear program and negotiate constructively and in earnest with the international community."

Iran Urged to Allow Jail Visits

Amnesty International urged Iran on Wednesday to open its prisons to international monitors and halt the use of executions as a "lethal instrument of repression" as protesters plan to mark the anniversary of last year's disputed presidential election.

A statement by the London-based rights group is among

a wave of denunciations against Iran's leadership timed to coincide with the one-year anniversary Saturday of the election, which set off the nation's worst internal upheaval since the 1979 Islamic Revolution.

Iranian authorities have carried out widespread arrests

and crackdowns to quell violent street protests that erupted after the June 12, 2009, reelection of President Mahmoud Ahmadinejad.

Amnesty urged Iranian leaders to allow U.N. human-rights observers to visit jails and other detention facilities to investigate allegations of abuses, rape, and torture.

The group also accused Iran of carrying out the hangings of five Kurdish activists in May to send a "clear message" to dissidents seeking to revive street demonstrations on the election anniversary.

- Associated Press

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