The United States announced Thursday that top officials will fan out starting next week to China, the United Arab Emirates, and other key countries in support of tighter sanctions against Iran.

"China is of concern to us in this regard," Robert Einhorn, the US State Department's special adviser for nonproliferation and arms control, told the House Oversight and Government Reform Committee.

Einhorn said he and Deputy Assistant Secretary of the Treasury for Terrorist Financing and Financial Crimes Daniel Glaser would visit China at the "end of August" as part of a push to "raise this at the highest levels."

"We need for them to enforce the Security Council resolutions conscientiously and we also need for them not to 'backfill' when responsible countries have distanced themselves from Iran," he said.

Glaser and Einhorn were first bound for Japan and South Korea next week as part of a push by Washington to get its partners in Asia, the Middle East and South America to tighten the vise on Iran over its suspect nuclear program.

A top US Treasury official in charge of sanctions, Stuart Levey, will head to the United Arab Emirates, Lebanon, and Bahrain next month, while another will travel to Brazil and Ecuador, according to the department.

A top international affairs and trade official at the US Government Accountability Office, the US Congress's investigative arm, said China was "aggressive" in investing in Iran's energy sector despite the sanctions.

The official, Joseph Christoff, told the same hearing that the United States had to "turn our attention" to China because international and unilateral sanctions were "not changing their behavior."

"The Chinese will argue that they have important security needs" related to getting energy for their booming economy, said Einhorn. "In our view they are overachieving in terms of their energy security needs."

"We think they have to rebalance their priorities," said Einhorn, who underlined that China "is going to be the focus of very high-level attention over the next weeks and months" on the issue of Iran.

Christoff also called for "a concerted focus on the United Arab Emirates," which has historically close ties to Iran and "is now the number one exporter of goods and services" to the Islamic Republic.

The lawmakers were weighing the effectiveness of recent legislation aimed at sharply tightening the economic grip on Iran over what the West charges is a covert nuclear weapons program and Tehran insists is a civilian power effort.

Republican Representative Dan Burton said he was "not optimistic it is going to work" because of the president's power to waive key sanctions in the name of national security.

"This may be one of the last chances we have," said Burton, who drew parallels to Adolf Hitler's rise in 1930s Germany and warned Iranian President Mahmoud Ahmadinejad "can be equated with, possibly, Hitler."

Democratic Representative Dennis Kucinich heaped scorn on US officials whose warnings about military action against Iran suggest they think "we can afford still another war" with US troops still in Iraq and Afghanistan.

"What we ought to be looking for is a more effective means to engage Iran," he said. "It's pretty clear that sanctions have been proved to be a failed policy."

The United States has hailed a new round of UN sanctions against Iran, as well as fresh sanctions adopted by the US Congress, and punitive steps taken by the European Union, Australia, and Canada.

The moves aim to get Iran to freeze its uranium enrichment program and revive moribund talks between Iran and six world powers -- Britain, China, France, Germany, Russia and the US.

Einhorn said US Secretary of State Hillary Clinton could soon announce steps against an handful of companies that fell afoul of US laws that prohibit doing business in Iran, notably its energy sector.

"I would say that she, before very long, will have to make determinations under the law as to the sanctionability of this relatively small number of cases, fewer than 10," he said.

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Australia tightens sanctions on Iran
Australia Thursday tightened its sanctions on Iran in a fresh bid to convince Tehran to allay international concerns over its nuclear drive.

Foreign Minister Stephen Smith said the new measures target more than 100 Iranian groups and companies, and restrict Australian business dealings with the country's oil and gas sector.

"In adopting this package, Australia stands at the forefront of international community efforts to have Iran meet its international obligations in relation to its nuclear program, one of the most serious security challenges facing the international community," he said.

The measures also include a ban on trading weapons and items which could be used for nuclear, chemical or biological arms or missiles.

They follow this month's new United Nations Security Council resolution against Iran and fresh sanctions announced by the European Union and Canada.

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Iran says to stop high grade enrichment if import deal holds
Iran will suspend uranium enrichment to 20 percent if it acquires nuclear fuel for a research reactor, the country's atomic chief said on an Iranian television channel on Thursday.

"We will not need to enrich to 20 percent if our needs are met" for fuel to power the Tehran reactor, Ali Akbar Salehi said, quoted by Al-Alam Arabic-language channel.

"We started enriching to 20 percent to meet our needs. We have no wish to draw on our reserves" of 3.5-percent enriched uranium (low-enriched uranium, or LEU) to produce 20-percent enriched uranium, he added.

In February, President Mahmoud Ahmadinejad said Iran has already produced highly enriched nuclear material in defiance of the West to power the reactor amid deadlock over a stalled nuclear swap deal.

The UN Security Council has imposed four rounds of sanctions against the Islamic republic, demanding it stop enriching uranium in a programme which Western powers fear conceals efforts to make a nuclear weapon.

Tehran insists that its atomic programme is peaceful.

In May, Turkey and Brazil brokered a deal under which Iran agreed to send 1,200 kilograms of LEU to Turkey, in return for high-enriched uranium to be supplied later by Russia and France for the Tehran reactor.

However, the fuel swap deal was cold-shouldered by world powers, which backed a fourth round of UN sanctions against Iran in June.