Iran's Supreme Leader Ayatollah Ali Khamenei told military commanders on Sunday the United States had created the "myth" of nuclear weapons to portray Iran as a threat, hardening his rhetoric before nuclear negotiations resume this week.

Khamenei, the highest authority in Iran, has supported the talks but continues to express deep mistrust of the United States.

"They created the myth of nuclear weapons so they could say the Islamic Republic is a source of threat. No, the source of threat is America itself, with its unrestrained, destabilizing interventions," Khamenei said in a televised address to a hall of several hundred military commanders.