Washington, Oct 12 (IANS): The US issued a worldwide travel alert for Americans Tuesday after a plot to assassinate Saudi Arabia's ambassador to Washington was exposed.

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

The alert said the "Iranian-backed plan to assassinate the Saudi ambassador may indicate a more aggressive focus by the Iranian government on terrorist activity", which was aimed at diplomats from certain nations, including the US.

The worldwide terror alert, which will expire Jan 11, came after the US Justice Department Tuesday accused two men, including an Iranian-born US citizen, of conspiring to kill the Saudi Arabian envoy Adel al-Jubeir and planning bomb attacks against Saudi and Israeli embassies in the US, reported Xinhua.

Iran's foreign ministry spokesperson Ramin Mehmanparast Tuesday rejected the US accusations, terming them as an "incorrect" and "prefabricated scenario", the semi-official Fars news agency reported.