Iran''s former president Mohammad Khatami confirmed he was pulling out of the June presidential election to avoid splitting the votes of the reformist front, in a statement published on Tuesday.

Khatami said he would back moderate candidate Mirhossein Mousavi.

"I announce my withdrawal from candidacy ... to preserve unity among the reformist front and to avoid a split of votes," Khatami said, confirming comments to Reuters by his allies on Monday.

Analysts say the move may boost hard-line President Mahmoud Ahmadinejad''s chances of re-election. Khatami was considered his main pro-reform challenger.

Khatami, who served from 1997 to 2005, oversaw a thaw in Iran''s ties with the West. Those relations have since sharply deteriorated under Ahmadinejad, who is expected to seek a second four-year term in the June 12 vote.

Mousavi, prime minister during the 1980-88 Iran-Iraq war, and reformer and former parliament speaker Mehdi Karoubi, have both announced they will run. Ahmadinejad is so far the only leading conservative to let it be known that he will stand.

"I believe ... Mousavi has the necessary competence to change the current situation," said Khatami.