US says it busted Iran plot to murder Saudi ambassador

In an explosive twist to bitter bilateral showdown:

US: The United States said Tuesday it had broken up a "chilling" plot planned high up in the Iranian government to assassinate the Saudi envoy to Washington, and vowed to hold Tehran to account.

In an explosive twist to the bitter US showdown with the Islamic Republic, the Justice Department charged two men with conspiring with Iranian government factions to blow up Saudi Ambassador Adel al-Jubeir on American soil.

"The complaint alleges that this conspiracy was conceived, sponsored and directed from Iran and constitutes a flagrant violation of US and international law," said US Attorney General Eric Holder.

"In addition to holding these individual conspirators accountable for their alleged role in this plot, the United States is committed to holding Iran accountable for its actions."

A criminal complaint named Manssor Arbabsiar, a 56-year-old naturalized US citizen holding Iranian and US passports, and Gholam Shakuri, an Iran-based member of the Quds Force, a unit of the Iranian Islamic Revolutionary Guard Corps.

Shakuri remains at large while Arbabsiar was arrested on September 29 at New York's John F. Kennedy airport and appeared in court Tuesday in Manhattan.

His lawyer said he would plead not guilty, if charged.

The alleged attempt, dubbed a "Hollywood" scenario by one top US official, was broken open by a paid US source posing as a member of a "violent" Mexico-based drug cartel known for "numerous" assassinations and murders.

The defendants believed the cartel would provide explosives for an attack on the ambassador, according to the complaint.

One official said the assassination could have been followed by other "lethal" attacks plotted by Iran. Unconfirmed media reports said the Saudi and Israeli embassies in Washington could have been targets.

Mexico said it cooperated closely with the US investigation and said Arbabsiar was arrested after he was denied entry to the country and sent away on a flight to New York, where he was arrested by US authorities.

"By strictly adhering to national and international regulations, we were able to neutralize a significant risk to Mexico's national security," the Mexican embassy in Washington said.

An aide to Iran's President Mahmoud Ahmadinejad dismissed the allegations as a "prefabricated scenario" designed to "turn public attention away from domestic problems within the United States."

But US Secretary of State Hillary Clinton said the United States would consult its allies about how to "further isolate" Iran. AFP