Six major powers wrapped up what they said was a "very constructive" meeting here Wednesday on fresh UN sanctions against Iran over its nuclear program, but diplomats cautioned against expecting early adoption.

"We have just had a very constructive consultation," China's UN Ambassador Li Baodong told reporters as he emerged from the closed-door meeting held at the US mission to the United Nations.

"We now have a better understanding of each other's positions. We will continue these consultations."

The meeting brought together envoys from the five veto-wielding members of the UN Security Council -- the United States, Britain, France, Russia and China -- plus Germany.

The French, British and Russian ambassadors also described the meeting as "constructive."

Diplomats earlier said envoys of four Western powers were trying to enlist the support of their Russian and Chinese counterparts for a fourth set of UN sanctions aimed at persuading Tehran to halt its uranium enrichment program.

On the table was a US draft resolution outlining sanctions in five areas: arms embargo, energy, shipping, finance and targeted punitive measures against Iran's powerful Revolutionary Guards, a diplomat familiar with the discussions said.

But others said they anticipated drawn-out discussions on the text and hinted that a vote by the full 15-member council might not take place until June.

In Washington, the US State Department meanwhile expressed doubt Wednesday that new attempts at dialogue could convince Iran to change course on its nuclear program, but said nations had the right to try anyway.

"We would disagree with those who would say, you know, put this (sanctions) on hold because we still think this has promise," State Department spokesman Philip Crowley said of any new dialogue attempts.

But he stopped short of saying nations should give up on such efforts, saying it remained "the right of any country to try to convince Iran to change course."

His remarks came in response to questions about Turkey, a key US ally that has been reluctant to support new sanctions against Tehran, seeking instead to promote dialogue with the Iranian regime.

Like Brazil, which is also cool to new sanctions on Iran, Turkey is a non-permanent member of the Security Council.

"We started to negotiate on the basis of the (US) text," said French ambassador Gerard Araud of Wednesday's six-way talks. "All six countries are on board (for future negotiations). We are getting into the substance. We are moving forward."

Russian Ambassador Vitaly Churkin said the six nations would meet again on the issue "very soon."

The United States and its Western allies believe Tehran is using uranium enrichment as a cover to build nuclear weapons, a claim Iran denies.

In Washington earlier Wednesday, US Undersecretary of State for Political Affairs William Burns spoke of "a sense of urgency" in crafting a fourth UN sanctions resolution in the face of Iran's continued refusal to freeze enrichment.

"We are working aggressively to adopt concrete measures that will serve as a platform to strengthen and expand upon existing sanctions and target the power centers mostly likely to have an impact on Iran's strategic calculus," he told the Senate Armed Services Committee in Washington.

A top US military official said Wednesday that Iran could make enough highly enriched uranium for a nuclear bomb in one year, but would likely not have the know-how to complete a weapon for 3-5 years.

General James Cartwright, the number two uniformed US officer, told the Senate Armed Services he was making "a historical estimate" not specific to Tehran and underlined that he could not predict "what problems they will encounter."

And Lieutenant General Ronald Burgess, the head of the US Defense Intelligence Agency, said Washington has not determined that Iran has decided to develop highly-enriched uranium.

The proposed US draft, which incorporates comments from Washington's European allies, includes sanctions targeting Iran's energy, arms, shipping and financial sectors, sources said.

But diplomats said Russia and China were opposed to any ban on investments in the energy sector and were likely to resist measures that would authorize seizures of cargo suspected of containing materials linked to Iran's nuclear activities.

The US draft would also expand sanctions against Iran's elite Revolutionary Guard Corps, a pillar of the regime and the driving force behind its controversial nuclear program.

earlier related report
Iran: U.S. tries to plug gaps in sanctions
Manama, Bahrain (UPI) Apr 14, 2010 - China is showing signs of going along with economic sanctions against Iran, one of its main oil suppliers, and Russia energy giant Lukoil is to cut gasoline supplies to the Islamic Republic and has abandoned a major energy project there.

But that still leaves serious loopholes in the U.S. strategy of isolating Iran, and one in particular: the freewheeling Gulf emirate of Dubai, which is suspected of being the site of ran's illicit trading lifeline.

Dubai, which until its recent meltdown was the financial powerhouse of the United Arab Emirates, has for years been the main gateway to Iran, particularly the port of Bandar Abbas 100 miles to the east across the Gulf.

Much of the contraband that flows to Iran is believed to go through Dubai. The volume of legitimate trade with Iran totaled an estimated $12 billion in 2009, making it easy to hide illegal goods bound for the Islamic Republic.

Dubai is packed with Iranians and posses of shady characters from the demi-monde of global terrorism; organized crime and hard-nosed entrepreneurs of dubious repute, all busily intriguing and plotting.

Sanctions-busting is bread and butter for them. Corruption is rife and many cargoes leave the Creek, the center of Dubai's trading activity, for Iran without being checked.

Those include goods legitimately shipped by U.S. companies to Dubai - and then re-exported to Iran, sidestepping U.S. prohibitions.

Michael Jacobson of the Washington Institute for Near East Policy, a pro-Israel think tank, observed: "One of the primary means of evading these regimes is through re-exports.

"Generally export-control laws distinguish between different countries in determining the legality of a specific transaction. For example, dual-use goods, which can have commercial or military applications (including in the nuclear sector), may be sent to some countries, but not to others.

"Iran often takes advantage of this framework, evading U.S. laws and international sanctions by setting up front companies and middlemen in countries to which these types of items can be legally exported.

"In most cases, the sellers are not told that the goods will be re-exported to Iran -- though many other sellers are willing to turn a blind eye."

Dubai is seen as one of these hubs, but there are others in Europe, Malaysia, Thailand, Hong Kong and Singapore, all extensively involved in re-exporting to Iran.

The Jan. 19 assassination in Dubai of Hamas arms procurer Mahmoud al-Mabhouh, allegedly by Israel's foreign intelligence service, underlined the emirate's links with Iran.

Tehran has become the main arms supplier to Hamas in the Gaza Strip and Mabhouh was reportedly in Dubai to acquire Iranian rockets.

There are an estimated 8,000 Iranian businessmen and 1,200 trading companies based in Dubai, Simon Henderson, a veteran British Middle East analyst who specializes in the Gulf, said.

"Dubai has a track record of eschewing bureaucratic obstacles to trade and downplaying international dangers," he noted. "Until late 2001, for example, it served as a financial center for al-Qaida."

The disgraced Pakistani nuclear scientist A.Q. Khan used Dubai as a trans-shipment hub for the nuclear arms black market he ran throughout the 1990s, helping Iran, North Korea and Libya set up clandestine nuclear weapons programs.

A week before Mabhouh was killed in a five-star Dubai hotel, Vanity Fair magazine reported that the CIA had tracked Khan to Dubai during one of his many visits to the emirate and had planned to assassinate him there. It said the operation was called off "because of a lack of political will in Washington."

People in Dubai are also believed to be deeply involved in banking and financial deals that benefit Iran and help it keep the wheels of commerce and industry turning.

Western efforts to cripple Iran include restricting the activities of Iranian banks abroad and preventing Tehran from skirting a global crackdown on transactions by simply opening new banks in foreign countries.

Iran has been targeted in several earlier sanctions regimes and was able to circumvent them to a large degree. Freezing its assets, one of the mainstays of these efforts, hasn't been particularly effective.

The Wall Street Journal reported that under the current set of sanctions only $43 million in Iranian money has been frozen in the United States -- one-quarter of what the Islamic Republic earns in oil revenue in one day.