Major General Hossein Salami, 58, replaces Major General Mohammad Ali Jafari, who had headed the Guards since September 2007.

The move comes less than two weeks after the United States branded Iran's Revolutionary Guard Corps as a "foreign terrorist organisation", adding it to a blacklist.

"Considering your capabilities and significant experience with different revolutionary responsibilities ... I promote you to major general and commander-in-chief of the Revolutionary Guards," Khamenei's statement read.

Salami, who had served as deputy head of the corps for nine years, is a veteran of the 1980-88 Iran-Iraq war. He had also led the corps' airforce before becoming the second-in-command.

The shuffle was caused by the "necessity of a change in Sepah's (the Guards' Farsi name) leadership" requested by Jafari himself, according to the leader.

Born in 1957 and majoring in architecture before the 1979 Islamic revolution, Jafari became a member of the Guards in 1981 and was promoted to the corps' head in 2007.

Quoted by ultraconservative Fars news agency, then Brigadier-General Salami advised Israel's Prime Minister Benjamin Netanyahu in October "to practice swimming in the Mediterranean because soon you will have no choice, but flee into the sea."

Salami also reportedly said that day that Israel could be destroyed by Iran's Lebanese ally Hezbollah.

"They are not at the level of being a threat for us. Hezbollah is enough for destroying them," Fars quoted him as saying.

Formed shortly after the 1979 Islamic Revolution, the Guards are estimated to be about 125,000 strong by the International Institute for Strategic Studies (IISS).

They answer to Khamenei and boast their own ground, naval and air forces.

Working in parallel to the regular army, the corps' mission is to "guard the (Islamic) revolution and its achievements" as well as "to realise holy ideals and to propagate the rule of God's law".