TEHRAN (Reuters) - Iran's hardline President Mahmoud Ahmadinejad warned his political rivals on Friday that their efforts to drive a wedge between him and Supreme Leader Ayatollah Ali Khamenei would come to nothing.

Iran's disputed presidential poll on June 12 plunged the country, the world's fifth biggest oil exporter, into its biggest internal crisis since the 1979 Islamic revolution and exposed deep divisions in its ruling elite.

Added to the widespread popular unrest and the wrath of reformists over the disputed election, Ahmadinejad has come under fire from his own allies and lost two hardline cabinet members by defying Khamenei over his choice of vice president.

But Ahmadinejad denied any rifts among the leaders.

"This is not a political relationship ... our relationship is based on kindness. It is like a relationship between a father and his son," Ahmadinejad said in a speech in the holy Shi'ite city of Mashhad.

"Your efforts will bear no fruit. This road is closed for those devils who dream about harming our relationship. Their dream will be buried along with them," state television reported.

Khamenei, who endorsed the election result and sided openly with Ahmadinejad, reacted firmly when the president named Esfandiar Rahim-Mashaie as his deputy.

In an Islamic system in which the Supreme Leader's word is supposed to be final and obeyed, Ahmadinejad ignored Khamenei's order for a week.

In the past few days, some hardline backers of the president and conservative media have made unusually blunt comment on the affair, saying Ahmadinejad has challenged the authority of Khamenei, Iran's most powerful figure.

"FOMENTING INSTABILITY"

Hardline cleric Ahmad Jannati, head of Iran's top legislative body, also criticized Ahmadinejad.

"Such appointments hurt your supporters ... A key position should not be given to a person who is not respected," Jannati told worshippers at Tehran University. His speech was broadcast live on state radio.

The disarray in the hardline camp is likely to complicate his job of forming a new cabinet. Jannati urged the parliament to help Ahmadinejad over the new cabinet.

Jannati said the vote was Iran's "healthiest" since the revolution, adding Iran's moderate defeated candidate Mirhossein Mousavi should go on trial for fomenting instability in Iran.

Mousavi and other leading moderates say the vote was rigged, calling the new government "illegitimate."