Moqtada Al-Sadr (file photo)

Iraq's powerful radical Shi'ite cleric Muqtada al-Sadr has issued a rare statement to his followers, explaining why he has not been seen in public since May of last year.

In the statement, reportedly distributed in Najaf and on the Sadrists' website, al-Sadr said he missed his followers, but that he needed time to "worship." The Shi'ite militia leader earlier resumed studies toward attaining the title of ayatollah, with the power to issue decrees.

Al-Sadr, who has one of the largest blocs of legislators in parliament and commands a formidable militia force, also admitted to splits in his movement.

He said many followers have left for what he called "materialistic reasons" or because they wanted to be independent.

The statement comes two weeks after he extended a truce between his Mahdi army militia and U.S. and Iraqi forces for another six months.

Friday, an explosion targeting a police station killed four policemen and wounded 17 others in western Mosul. This, after twin bomb attacks in Baghdad Thursday killed at least 68 people and wounded more than 120 others.

There has been no claim of responsibility for the attacks in the capital's Karrada neighborhood.

The attacks occurred despite an overall drop in violence since the U.S. military sent 30,000 extra troops to Iraq last year.

Some information for this report was provided by AP and Reuters.