After the United States accused Iran of backing a plot to kill Saudi Arabia's ambassador to Washington, the State Department issued a worldwide travel alert for U.S. citizens late on Tuesday.

The Department of State alerts U.S. citizens of the potential for anti-U.S. actions following the disruption of a plot, linked to Iran, to commit a significant terrorist act in the United States, the statement reads.

U.S. citizens residing and traveling abroad should review the Department's Worldwide Caution and other travel information when making decisions concerning their travel plans and activities while abroad.

The State Department also encourages all U.S. citizens to enroll in the Smart Traveler Enrollment Program (STEP), which makes it easier for the embassy/consulates to contact travelers in case of emergency.

The Travel Alert expires on January 11, 2012.

The U.S. said two men, including an Iranian-born American, conspired to kill the Saudi Arabian envoy and carry out bomb attacks against Saudi and Israeli embassies.

An Iranian-born U.S. citizen, working on behalf of the Iranian Islamic Revolutionary Guard Corps Qods Force - designated by the Treasury Department in 2007 for its support of terrorism - is suspected of conspiring to assassinate the Saudi Arabian Ambassador to the United States, according to the Travel Alert.

U.S. authorities said earlier on Tuesday that they had thwarted the plot and one man, 56-year-old Mansour Arbabsiar, was arrested last month. The other suspect was believed to be in Iran.

Meanwhile, Iran denied the charges and expressed outrage at the accusations calling them fabricated and baseless.

Saudi Arabian officials said it was despicable.

The burden of proof is overwhelming... and clearly shows official Iranian responsibility for this. Somebody in Iran will have to pay the price, senior Saudi prince Turki al-Faisal, a former ambassador to Washington, said in a statement from London.

U.S. President Barack Obama called the plot a flagrant violation of U.S. and international law.

Secretary of State Hillary Clinton urged America's allies to work together to set up sanctions and further isolate the Middle Eastern country from the West.

The complicated plot involved monitoring international calls, Mexican drug money, and an attempt to blow up the ambassador in a Washington restaurant, according to FBI Director Robert Mueller.

American travelers in foreign countries can stay up to date on the alert by bookmarking the Bureau of Consular Affairs Web site, which contains current Travel Warnings and Travel alerts as well as the Worldwide Caution.