Saudi Arabia on Wednesday denounced an alleged assassination plot against its ambassador to Washington as "outrageous and heinous" but said it was still trying to determine who was behind it.

The statement, issued after it was reviewed by King Abdullah, did not name Iran nor did it focus on the involvement of an officer of Iran's Quds force, the special operations unit of the Revolutionary Guard Corps that U.S. Attorney General Eric Holder linked to the alleged plot on Tuesday.

But an adviser to the Saudi government said that Gholam Shakuri, named in the U.S. Justice Department's criminal complaint as the Iranian official supporting the plot, was already known to the Saudi government as one of the officers who directed Iranian support to Shiite Muslims in Bahrain when they rose up in February to demand political rights from the minority Sunni regime.

"The officer does exist, and we have known him for a while," said the adviser, Nawaf Obeid. He said that based on telephone intercepts and other intelligence, the Bahraini and Saudi governments believe that Shakuri, a colonel, had urged protesters to go to the Saudi embassy and backed a plan to take control of Bahrain's state television.

The Saudi reluctance to name Iran as the ultimate source of the alleged plot came as officials in Washington attempted to use the purported conspiracy to rally support for tougher international sanctions.

Pressing on a variety of fronts to raise international awareness of the plot, the State Department summoned the entire Washington-based diplomatic corps for a briefing on the matter, ordered its diplomats abroad to brief their host governments on the alleged conspiracy, and arranged for U.S. Ambassador to the United Nations Susan Rice to provide details of the investigation to members of the U.N. Security Council.

Secretary of State Hillary Clinton called the plot a "dangerous escalation" in Iran's support for terrorism and urged the rest of the world to condemn Iran for it. "Iran must be held accountable for its actions," Clinton said. Vice President Joe Biden in a television appearance called on the world to present unified front against Iran.

Officials from the FBI, CIA, Justice Department, State Department, and Treasury Department also briefed members of the Senate intelligence and armed services committee members. Afterwards, two members of the committee said that while the charges were serious, they did not merit a U.S. military response.

"This was not an action directed at the United States. It was an action directed at an ally of the United States, said Sen. Saxby Chambliss, R-Ga., a member of the Senate Armed Services Committee, who said he favored economic sanctions imposed on those allegedly involved in the plot.

Sen. Dianne Feinstein, D-Calif., chair of the Senate Intelligence Committee, agreed U.S. military action was not merited. But she said the alleged plot "should be taken very seriously."

Prince Turki al Faisal, a former Saudi intelligence chief who served as Saudi ambassador to Washington until the current ambassador, Adel al Jubeir, took over in 2007, demanded that Iran be punished.

"The burden of proof is overwhelming, and clearly shows official Iranian responsibility for this," he said while in London. "Somebody in Iran will have to pay the price."

But that tough talk was at odds with the general tone of Saudi commentary, which included discussion of the bizarre nature of the plot, in which a used car salesman of Iranian origin in Texas was thwarted in his alleged attempt to hire a killer because the contractor he chose was an undercover agent for the U.S. Drug Enforcement Administration.

"I immediately heard people saying it was an amateurish plan," said Jamal Khashoggi, former editor of a leading Saudi daily who's now setting up a 24-hour Arabic news channel. "It is strange, but I'm sure the American prosecutors have valid information."

Khashoggi went on to say that that many plots look amateurish until they become reality. "If I caught the 9/11 plotters one week ahead of that time, I might have said the same thing," he said. "If these guys succeeded, it wouldn't look like amateurism."

Obeid called it a "Mickey Mouse operation" but added: "There is no claiming that this is not a plot. The only thing we are skeptical of is how real it is."

Iran Wednesday ridiculed the U.S. charges for the second day running.

Ali Akbar Salehi, the foreign minister, said they involved "already failed, funny and ridiculous scenarios," according to IRNA, the official Iranian news agency.

Salehi said it was "illogical and irrational" to accuse Iran of sponsoring terrorism as it had been the victim over the past three decades. "World public opinion will never accept such an allegation against Iran," he said.

The speaker of Iran's parliament, Ali Larijani, called the allegations "silly" and said the U.S. had leveled them " to divert attention from internal and regional problems."

On Tuesday, Iran's permanent representative to the U.N., Mohammad Khazaee, rejected what he said were "fabricated and baseless allegations."

U.S. officials in Washington, however, defended the investigation, noting that they, too, were skeptical when they first learned of it and only became convinced it was real after what one senior official called "a rigorous examination." The official spoke on condition of anonymity because of the sensitivity of the matter.

The official said investigators still had not reached a firm conclusion on what would have motivated the attack. The official noted that the Quds Force is suspected of involvement in the 1996 bombing of the Khobar Towers in Saudi Arabia, which killed 19 U.S. service members and of providing assistance to anti-U.S. militant groups in Iraq.

Just how Saudi Arabia, the world's top oil producer and the richest country in the region, will respond to the alleged plot wasn't immediately clear.

Among the ideas said to be under discussion here are a boost in oil production, which would lead to lower prices and a weakening of the Iranian economy, already battered by international sanctions over its nuclear development program; a tougher Saudi stance on Syria, where Iran backs the government, which is dominated by the minority Alawite sect, which is related to Shiite Islam, and Saudi Arabia has been supporting the anti-government protesters, who are primarily from the Sunni majority; and a new drive to further isolate Iran throughout the Middle East.

Saudi-Iranian relations have grown increasingly tense since May 2008, when Shiite militants, backed by Iran, took over Beirut and were reported to have attacked the Saudi embassy and the living quarters of its then-ambassador, Abdulaziz Khoja, a poet and writer who's now the country's information minister. Khoja was forced to flee for his life, first to Christian East Beirut and then to Cyprus, by boat., according to Obeid.

Both sides engage in harsh rhetoric, but they have thus far stopped well short of turning it into action.

(Greg Gordon and William Douglas contributed to this report from Washington.)