Iran's supreme leader, Ayatollah Ali Khamenei, dismissed Saturday U.S. allegations of a Tehran-sponsored assassination plot as "absurd," in his first direct reaction to the claim.

"It's a meaningless and absurd accusation regarding a number of Iranians," he told a crowd in the western city of Gilangharb in a speech carried by state television.

Lebanese Forces leader Samir Geagea warned that the Lebanese status quo was in tatters after the U.S. accused Iran of trying to assassinate the Saudi ambassador in Washington.

In an interview with the Saudi al-Riyadh daily, Geagea said: “After the confrontation between the U.S. and Saudi Arabia on one side and Iran on the other went out of hands, I am no longer sure that we could keep this status quo.”

The United States is seeking international support for fresh sanctions against the Central Bank of Iran, a Treasury official said Friday following an alleged plot to kill the Saudi envoy in Washington.

"We are engaging in an effort to develop the multilateral support that would be critically important in having an action against the CBI really be effective," sanctions czar David Cohen told the House Foreign Affairs Committee.

British Foreign Secretary William Hague said Thursday that an alleged Iranian-backed plot to kill the Saudi envoy to the United States is a "major escalation in Iran's sponsorship of terrorism."

Hague said London was in "close touch" with U.S. authorities and would work to agree an international response along with the United States, European Union and Saudi Arabia to the U.S. charges, which Tehran denies.

Iran on Thursday urged Saudi Arabia "not to fall into the trap" of believing U.S. claims that Tehran was behind an alleged plot to assassinate the Saudi ambassador to Washington, saying the accusations only served the United States and Israel.

"I am asking Saudi Arabia not to fall into the trap, because any disturbance in relations between countries in the (Middle East) region will only benefit the United States and the Zionist regime," said Ali Ahani,Iran's deputy foreign minister in charge of Europe and America affairs, according to the IRNA news agency.

Saudi Arabia strongly condemned on Wednesday the "sinful and abhorrent" attempt to assassinate its ambassador to Washington, a day after the United States claimed Iran was behind the plot, SPA state news agency reported, quoting an unnamed official.

"The Kingdom strongly condemns the sinful and abhorrent attempt to assassinate the (Saudi) envoy... to the United States," SPA said, quoting the official.

A former chief of Saudi intelligence said Wednesday there was overwhelming evidence that Iran was behind a plot to kill the Saudi ambassador to Washington and must "pay the price".

"The burden of proof is overwhelming... and clearly shows official Iranian responsibility for this. Somebody in Iran will have to pay the price, whatever the level of these persons is," Saudi Prince Turki al-Faisal told a conference on oil in London.

Iranian Foreign Minister Ali Akbar Salehi on Wednesday warned the United States against "confrontation" over accusations Tehran plotted to assassinate the Saudi ambassador to Washington.

"We are not seeking confrontation; our policy is cooperation and interaction. If they want to impose a confrontation upon the Iranian nation, the consequences of this issue will be more severe for them," Salehi told reporters after a cabinet session, the ISNA news agency reported.

U.S. accusations Iran was involved in an alleged plot to kill the Saudi ambassador to Washington is a "childish game" meant to distract the U.S. public's attention, Iran's parliament speaker said Wednesday.

"The Americans have launched a stupid mischief. They want to divert attentions from the problems in the region," Ali Larijani said, according to Mehr news agency and other Iranian media.

Saudi King Abdullah will undergo new back surgery in Riyadh in the next few days, following two similar operations last year in the United States, the palace said in a statement on Tuesday.

Exams performed after the 87-year-old king complained of "pain in the lower back" revealed a stretched ligament, said the statement quoted by the Spa official news agency.