WASHINGTON - US authorities broke up an alleged plot to bomb the Israeli and Saudi Arabian embassies in Washington and assassinate the Saudi ambassador to the United States, court documents and a US official said on Tuesday.

The alleged plotters were identified as Manssor Arbabsiar and Gholam Shakuri -- both originally from Iran -- in the criminal complaint unsealed in federal court in New York City.

US Attorney General Eric Holder said one of two men charged in the plot, both originally from Iran, had been arrested and confessed.

Arbabsiar, a naturalized US citizen, was arrested in late September. Shakuri is still at large.

The plot was disrupted by the Federal Bureau of Investigation and Drug Enforcement Administration.

US officials said one overarching question is whether elements of the Iranian government were behind the plot. Court documents identified Shakuri as a member of the Quds Force, a branch of the Iranian Islamic Revolutionary Guard Corps.

Shakuri approved the plan to try to kill the Saudi ambassador during telephone conversations with Arbabsiar, the complaint said.

In July and August, Arbabsiar paid $100,000 to a DEA informant for the murder of Saudi ambassador Adel Al-Jubeir, court documents said.

Arbabsiar was arrested late last month at New York's John F. Kennedy International Airport. After his arrest, court papers said, Arbabsiar confessed to authorities.

The men are charged with one count of conspiracy to murder a foreign official, two counts of foreign travel and use of interstate and foreign commerce facilities in the commission of murder for hire and one count each of conspiracy to use a weapon of mass destruction and conspiracy to commit an act of terrorism.

"High-up (Iranian) officials in those agencies ... were responsible for this plot," Holder told a news conference. "I think one has to be concerned about the chilling nature of what the Iranian government attempted to do here," he said.

Iran swiftly rejected the allegation. "The Islamic Republic of Iran has rejected U.S. accusations of the country plotting to assassinate the Saudi envoy to Washington as a prefabricated scenario," state English language Press TV said, without elaborating or giving a source.