Iran's Ayatollah Ali Khamenei said that the US is one of "the most corrupt and cruel" governments in the world in the latest broadside as he promised that his theocratic nation would frustrate Washington in all departments they confront.

Speaking to the Council of Coordination on Islamic Propagation, the supreme leader took the opportunity to heap scorn on the US and President Donald Trump saying they would never win the psychological war against Iran.

"Our main enemy, the American regime, rules one of the most corrupt and most oppressive countries. It supports terrorists. According to reports, it's still supporting Daesh [Arabic name for Islamic State] and others like them. The American government supports the cruel House of Saud in his crimes against Yemen, and it supports the Zionist regime in their crimes against Palestine," Khamenei said in his televised address on Wednesday (27 December).

Khamenei, who wields the highest political authority in Iran, continued, "The American government is trying to divide Iran. It is also profiting from help of some wealthy states in our region. They must know that we will advance, powerfully, with Divine favour, just as we did when we defeated them in our region. Just as we rubbed their noses into the dirt, we will go forward with great power. With Divine permission, we will frustrate America in all areas."

On Trump, the Iranian leader said the American president is bound to fail if he presses on with his harsh stance on Tehran. He said former US president Ronald Reagan was "more powerful and smarter" than Trump and even he could not bring down the Iranian regime.

Khamenei, who was Iran's president during most part of Reagan's two terms at the White House, said, "Reagan was more powerful and smarter than Trump, and he was a better actor in making threats, and he also moved against us and they shot down our plane. But Reagan is gone and, according to our beliefs, he now faces God's retribution... while Iran has made great advances in all areas since Reagan's time."

Khamenei was referring to the passenger jet, which was shot down by the US forces in 1988, killing all the 290 people aboard the aircraft. While the US said the plane was brought down by mistake, Iran insists it was a deliberate attack.

"They commit crimes in their own country; the US police kill black women, children and youth and are then acquitted in the court. This is their judiciary system. Then they criticise the judiciaries of other countries, including our faithful judiciary system," said Khamenei, who exhorted senior Iranian authorities to stay vigilant in monitoring any efforts by the US to destabilise Iran.

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Iran's Supreme Leader Ayatollah Ali Khamenei speaks to the audience in Tehran Handout via Reuters