JOIN USThe allegations were denied by the opposition National Council of Resistance of Iran (NCRI).
A police probe into one of the suspects, following an Interpol request, suggested the individual "is a member of the Mujahedeen-e Khalq Organisation," the Tehran mission in the United Nations said in a letter to UN chief Ban Ki-moon on Friday, the official IRNA news agency reported.
The letter did not explicitly identify or give the whereabouts of the suspect, but was apparently referring to Gholam Shakuri.
However, it said the new revelation proved that "US claims about the involvement of the Iranian government (in the alleged plot) do not border reality."
The United States alleges Shakuri is an Iranian official in the elite Quds unit, a shadowy special operations outfit in the Islamic republic's Revolutionary Guards, and that he co-conspired with an Iranian-American car salesman, Manssor Arbabsiar, to kill the Saudi ambassador to Washington.
While Arbabsiar is in US custody, American officials say they believe Shakuri is in Iran, and they have called on Tehran to turn him over to face charges.
Tehran has vehemently denied any involvement in the alleged plot, and accused Washington of seeking to divert attention from domestic economic woes and foreign policy failures in the Middle East and attempting to fuel tensions between Iran and its neighbours.
The NCRI yesterday told AFP Tehran's claims were "preposterous."
"It is a known tactic of the clerical regime that it tries to attribute its crimes to the opposition. The mullahs have used this tactic since the inception of their rule," said Mohammad Mohaddessin of the NCRI.
The Mujahedeen-e Khalq Organisation, also known as the People's Mujahedeen of Iran, is the main armed Iranian exile group that aims to overthrow Iran's Islamic regime.
The United States and Iran consider the group to be a terrorist organisation but it was removed from a list of 50 banned militant groups compiled by the European Union in January 2009.
On October 27, Iranian foreign minister Ali Akbar Salehi confirmed an Interpol request concerning Gholam Shakuri, hinting the suspect was a member of the Mujahedeen group.