Israel's defence minister on Monday accused Iran of using its embassies as terrorist bases and transferring guns and bombs through diplomatic pouches, without providing evidence for the claims.
The two regional foes are widely believed to be locked in a covert war over Iran's nuclear programme, with Tehran blaming Israel for the killing of its nuclear scientists and Israel accusing Iran and its Lebanese ally Hezbollah of terror attacks in third countries.
"Wherever there are Iranian embassies, they also serve as bases for espionage and terrorism," Israeli Defence Minister Moshe Yaalon said in a statement after meeting with visiting Guatemalan President Otto Perez.
"The Iranians use their diplomatic courier to transfer bombs and arms," he said, referring to pouches carried by diplomats that are not customarily subject to inspection.
"We know there are South American countries like Cuba, Venezuela, Nicaragua and Bolivia where the Iranians maintain terror bases in their embassies and among the local Shiite Muslim population," Yaalon said.
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Israel and Argentine authorities have long suspected Iranian involvement in the bombings of a Jewish centre and the Israeli embassy in Buenos Aires in the 1990s that killed scores of people, charges denied by Iran.
More recently, Israel blamed Iran and Hezbollah for the July 2012 suicide bombing of a bus packed with Israeli tourists in Bulgaria that killed six people and wounded 35 others. Bulgarian authorities also said Hezbollah was behind the attack.
Last week Hezbollah said a member of its secretive top leadership had been shot dead near Beirut and blamed Israel for the assassination. Israel denied responsibility.
Israel has long viewed Iran as its greatest threat because of Tehran's controversial nuclear programme, which Israel and Western nations suspect is aimed at covertly developing a nuclear weapons capability.
Iran insists its programme is entirely peaceful, and reached a landmark deal with world powers last month in which it will curb its nuclear activities in exchange for some relief from crippling international sanctions.
Israel was strongly opposed to the deal, and has not ruled out using military force against Iran's nuclear programme.