Grand Ayatollah Ali Al-Sistani warned that failure to participate in the election would allow others to achieve "illegitimate goals." He did not say who he was referring to or what their goals may be.

Iranian-born Al-Sistani has quietly guided Iraq's young democracy since the 2003 overthrow of Saddam Hussein's regime. The country's ruling establishment reveres him, partly out of respect for his spiritual leadership but also for fear that ignoring his wishes could spark a backlash from the country's majority Shiites who wait on his every word.

Al-Sistani has made a point in the run-up to earlier post-Saddam elections to call on voters to turn out.

However, his latest call comes at a time when seething Sunni leaders are threatening to boycott over the ban of more than 400 mostly Sunni candidates for alleged ties to Saddam's outlawed Baath Party.

"His eminence (Al-Sistani) believes it's necessary for all citizens to participate -- men and women who are concerned with the future of the nation and with building it on the basis of justice and equality in rights and duties among all its sons," Al-Sistani's statement said.

"Not to vote, for whatever reason, will give others a chance to realize their illegitimate goals," it added.

His comments were in response to followers who sent in questions on the merit of participating in the vote, given what they see as the poor performance of lawmakers and officials who took office after the last parliamentary election in December 2005.

Al-Sistani, who is in his late 70s, lives in Najaf south of Baghdad. He does not grant interviews and rarely ventures out of his modest home on a narrow alley in the city's old quarter. His edicts, or fatwas, are few and far between. But they have helped shepherd the nation through the turbulent after Saddam's ouster.

In the latest statement, Al-Sistani said he did not support any particular coalition contesting the election, but stressed that voters should only give their votes to "the best and the most concerned with Iraq's interests at present and in the future."

Al-Sistani in the past has shown sympathy toward religious Shiite groups, particularly the Supreme Islamic Iraqi Council, a party established in Iran in the 1980s with the support of that country's ruling clerical establishment.

The Supreme Council has closely cooperated with the United States, but is known to be the closest Iraqi party to Tehran.