In a letter published by Iran's state news agency, the ayatollah said "certain grievances" between reformists and conservatives should be ignored in the interest of national unity.

Ayatollah Khamenei also called for what he termed a "healthy, lively and enthusiastic" climate for the upcoming parliamentary election.

Iran's main pro-reform party has said it will boycott the February 20 poll because of the conservative Guardian Council's ban on thousands of prominent reformist candidates. More than 120 reformist members of parliament have resigned.

Iran's most recent political crisis erupted some three weeks ago when the non-elected Guardian Council rejected 3,600 mostly reformist candidates, about a third of the election hopefuls.

The ayatollah ordered the Guardian Council to review its decision. It subsequently reinstated just over 1,000 candidates, leaving more than 2,000 unable to run.

Iran's reformist president, Mohammed Khatami, said Saturday he considers the election to be unfair. Nevertheless, he pledged to hold the vote on time because the ayatollah ordered it.

Reformists have held a majority of seats in Iran's parliament for the past several years. Reformists believe that the Guardian Council's mass rejection of candidates is an attempt to regain conservative dominance in parliament.

Analysts say many Iranian voters are disillusioned by the reformists' failure to enact change, and they expect a low turnout at the polls.