Iran has said it will hit Tel Aviv, US shipping in the Gulf and American interests around the world if it is attacked over its disputed nuclear activities.
"The first bullet fired by America at Iran will be followed by Iran burning down its vital interests around the globe," the students news agency ISNA quoted an aide to Iran's Supreme Leader Ali Shirazi as saying in a speech to Revolutionary Guards.
The United States and its allies suspect Iran is trying to build nuclear bombs. Tehran says its programme is peaceful.
"The Zionist regime is pressuring White House officials to attack Iran. If they commit such a stupidity, Tel Aviv and US shipping in the Persian Gulf will be Iran's first targets and they will be burned," Shirazi was quoted as saying.
Shirazi, a mid-level cleric, is Supreme Leader Ayatollah Ali Khamenei's representative to the Revolutionary Guards.
"The Iranian nation will never accept bullying. The Iranian nation is a nation of believers which believes in jihad and martyrdom. No army in the world can confront it," he added.
In Jerusalem, Israeli Prime Minister Ehud Olmert's spokesman, Mark Regev, declined to comment on the threat to hit Tel Aviv, saying only: "Shirazi's words speak for themselves."
Israel, believed to be the Middle East's only nuclear-armed power, has vowed to prevent Iran from acquiring an atomic bomb. The United States says it wants to resolve the dispute by diplomacy but has not ruled out military action.
In April, Israel's Infrastructure Minister Binyamin Ben-Eliezer, who is a former army general and defence minister, told Israeli media: "An Iranian attack will prompt a severe reaction from Israel, which will destroy the Iranian nation."
Shirazi's comments intensified a war of words that has raised fears of military confrontation and helped boost world oil prices to record highs in recent weeks.
"We will make the enemy regret threatening Iran," Mohammad Hejazi, deputy commander of the Revolutionary Guards, was quoted as saying by the semi-official Mehr news agency on Tuesday.
The Revolutionary Guards' commander of artillery and missile units, Mahmoud Chaharbaghi, said 50 brigades of his forces had been equipped with what he called smart cluster munitions.
"All our arms, bullets and rockets are on alert so that we would defend the Islamic Republic's territory," Hemayet daily quoted him as saying.
Senior officials from six world powers held a conference call yesterday to discuss the response Iran delivered on Friday to a revised package of incentives to curb its nuclear work.
The United States, France, Britain, China, Russia and Germany offered the package last month and said Iran must suspend its uranium enrichment work before formal talks on implementing it.
Iranian President Mahmoud Ahmadinejad said yesterday his country would not stop enriching uranium and rejected as "illegitimate" a demand by major powers that it do so.