TEHRAN: Iran's supreme leader Ayatollah Ali Khamenei on Monday formally endorsed Mahmoud Ahmadinejad as president for a new four-year term amid intense political turmoil in the Islamic republic.

"The supreme leader appointed Mahmoud Ahmadinejad as the president of the Islamic Republic for a second term," state-owned Al-Alam television said.

Ahmadinejad's confirmation comes as Iran grapples with its worst turbulence since the 1979 Islamic revolution, with deadly street protests, a raft of political trials and an escalating feud between rival factions.

Ahmadinejad, 52, is due to be sworn in before parliament on Wednesday following his June 12 election win, but is under fire from his own hardline camp, which questions his loyalty to Khamenei.

The announcement of Ahmadinejad's landslide victory was met with a vast outpouring of anger from opposition supporters who claim their votes were stolen.

Massive street protests left at least 30 people dead and saw several thousand protesters rounded up, among them prominent pro-reform figures and journalists.

Mir Hossein Mousavi and Mehdi Karroubi, who stood against Ahmadinejad, have accused the authorities of massive vote rigging and branded Ahmadinejad's presidency illegitimate.

His re-election has also created a rift among the clergy, with several senior clerics siding with the opposition and condemning the post-election violence and the regime's treatment of its critics.

The authorities hit back with a heavy-handed crackdown on protesters, whom they accuse of seeking to overthrow the regime.

On Saturday, around 100 people were put on trial in a Tehran revolutionary court, a move slammed by opposition leaders but welcomed by hardliners who accused Mousavi and former president Mohammad Khatami of treason.

Another 10 went on trial on Sunday.

In a keynote speech on June 19 after a week of bitter protests, Khamenei strongly backed Ahmadinejad and dismissed the vote-rigging allegations, accusing Western governments, Britain in particular, of instigating the unrest.

London dismissed the allegation and tensions rose after Iran detained nine local British embassy staffers on accusations of provoking riots. All have since been released.

Relations with the West worsened during Ahmadinejad's first term because of his frequent verbal attacks on Israel and his uncompromising stance on Tehran's nuclear drive, which world powers fear is a cover for weapons development.

Although key policy issues are decided by Khamenei, critics point the finger of blame at Ahmadinejad for three sets of UN Security Council sanctions over Iran's refusal to suspend uranium enrichment.

Opponents also accuse Ahmadinejad, who enjoyed windfall oil revenues in his first term, of mismanaging the economy, stoking inflation, wasting resources and manipulating statistics to cover his failures.

Ahmadinejad crossed swords with the all-powerful Khamenei after he appointed a controversial aide as his first vice president.

Khamenei intervened and ordered the sacking of Esfandiar Rahim Mashaie, an outspoken politician who had enraged hardliners by saying Iran was a friend of the Israeli people.

The fact it took Ahmadinejad a week to finally carry out Khamenei's order angered the conservative wing of the regime, who warned him to obey the supreme leader.

The hardline camp was further irked when Ahmadinejad sacked intelligence minister Gholam Hossein Mohseni Ejeie following a reported "quarrel" over Rahim Mashaie's appointment.

Ahmadinejad denies any rift with Khamenei, characterising his relationship with the supreme leader as one of "father and son."

Iran's crackdown on protesters drew international condemnation, including from arch-foe the United States.

After three decades of severed diplomatic ties, Washington this year made overtures to Tehran, offering talks over their long-standing disputes, including the nuclear issue.

Iran has yet to respond but has ruled out negotiations on the nuclear programme, insisting it is for solely peaceful ends.

Should Ahmadinejad stick to his guns on the nuclear programme, his second term is likely to be characterised by greater tension with the West, which has warned of tougher sanctions.

Iran's stance towards staunch US ally Israel is also likely to harden further with Ahmadinejad -- who has repeatedly said the Jewish state is doomed to disappear -- at the helm for a further four years.

Israel, the Middle East's sole if undeclared nuclear armed state, has not ruled out military actin to curb Tehran's atomic ambitions.