TEHRAN: Iran on Saturday hardened its denial of involvement in a thwarted assassination plot in Washington, with its supreme leader slamming the US accusations as "absurd" and without effect.
The remarks, the first direct response by Ayatollah Ali Khamenei, came as Iran's government again urged Saudi Arabia to be wary over the plot claims that Iranian officials tried to contract a Mexican drug cartel to kill the Saudi ambassador to Washington.
The US government is rallying other nations to its bid to further isolate Iran over the plot and has provided allies with details it says prove the outlandish assassination bid was genuine.
US President Barack Obama on Thursday warned Iran would be held to account over the alleged plot, which he described as part of a pattern of "dangerous and reckless" behaviour by Tehran.
Iran's strenuous denials of involvement, made ever since the alleged plot was made public Tuesday, were capped Saturday with Khamenei's speech.
"It's a meaningless and absurd accusation regarding a number of Iranians," he said in a speech carried by state television.
"But it has not stuck and it will not stick," he said.
Khamenei added defiantly: "They say that they want to isolate Iran. They are the ones who are isolated."
US officials admit they do not know which of Iran's leaders, if any, are implicated.
But Obama stressed that "even if at the highest levels there was not detailed operational knowledge, there has to be accountability with respect to anybody in the Iranian government engaging in this kind of activity."
The US Justice Department and FBI say the trail leads to officials inside the Quds Force, a special operations outfit within Iran's elite Revolutionary Guards.
Quds Force personnel are said to have transferred nearly $100,000 to the bank account used by a member of a Mexican drug cartel who was really a paid US informant who tipped off the FBI.
The money was allegedly a down payment for a $1.5-million-dollar hit on the Saudi ambassador, Adel al-Jubeir, possibly through the bombing of a Washington restaurant.
An Iranian used-car salesman who is a naturalised US citizen living in Texas, Manssor Arbabsiar, is said to have confessed to acting as the go-between for his cousin, whom he described as a high-ranking official in the Quds Force, and the Mexican cartel.
Arbabsiar is in US custody, charged with the plot.
The US Justice Department has also charged another Iranian identified as Gholam Shakuri, who is said to be an Iran-based Quds Force operative who flew to the United States to speak with Ababsiar. Shakuri is now believed to be in Iran.
Saudi Foreign Minister Prince Saud al-Faisal has said his country "will find a suitable response" against Iran for the alleged plot.
But Iran's foreign minister, Ali Akbar Salehi, on Saturday said: "We hope the Saudis will deal with this issue with caution."
He accused the United States of trying to create divisions in the Middle East but said "Saudis were too wise to get involved in this political game," according to the Fars news agency, citing comments Salehi made on state radio.
Initial US actions following the alleged plot revelation seem to be focused on adding to US and UN sanctions already imposed on Iran over its controversial nuclear programme.
A US Defence Department spokesman on Wednesday downplayed the possibility of US military action against Iran, though he said the final decision rests with Obama.
While the US president has said "we don't take any options off the table in terms of how we deal with Iran," he suggested increased economic, political and diplomatic pressure would be the tools used.
Sanctions experts, including former US Treasury Department officials, say that successive rounds of sanctions have left only a few big targets.
If they were subject to US or multilateral restrictions, it could have devastating effects on Iran's economy, and its population of 75 million.
At the pinnacle of the target list is the Central Bank of Iran, or Bank Markazi, which sits at the centre of Iran's financial and energy interests.
While the US government already bans its citizens and entities from doing business with Bank Markazi, convincing Europe to join in could profoundly reduce government revenues and destabilise Iran's currency, say experts such as Avi Jorisch, a former advisor at the Treasury Department's office of terrorism and financial intelligence.
"Iran handles its oil business through the central bank," said Jorisch.
Oil sales account for 80% of Iran's foreign exchange revenue, and if the Iranian currency were laid low, Iranian civilians could find it very difficult to buy imported food and medicine.
There are other risks for Washington in such a move.
Choking off Iran's ability to sell oil in Europe, India or Japan, without pumping more from the likes of Saudi Arabia, could also result in significantly higher oil prices in the United States and Europe.
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