The group of Jordanian militant Abu Musab al-Zarqawi (search) claimed responsibility Tuesday for the assassination attempt against the leader of Iraq's largest Shiite Muslim party that killed and wounded dozens of people.

In a statement posted on an internet web site, al-Zarqawi's Al Qaeda (search) in Iraq said one of its members carried out the homicide attack near Abdel Aziz al-Hakim's (search ) office Monday that killed 15 people and wounded more than 50. Al-Hakim, who was not in the office but in his adjacent house, was not hurt.

The assassination attempt came a month before Iraq's general elections in which al-Hakim is running, while most Sunni Muslims are boycotting saying it should not be held under U.S. occupation and amid deteriorating security situation. Shiites, who make up 60 percents of Iraq's 26 million, want to show their strength through elections after living under Sunni domination for decades.

"On Monday morning, one of the lions of the martyrdom seekers brigades, belonging to the military wing of Al Qaeda in Iraq launched an attack in order to wipe out one of the symbols of treason for the Americans," the statement said.

It added that "We tell you Hakim that if one arrow missed you we have many more arrows."

U.S. officials have offered a reward of $25 million for the capture of al-Zarqawi. He is believed to be behind numerous high-profile attacks in Iraq, including last year's bombing of the U.N. headquarters, the beheading of several foreign hostages and the August 2003 killing of al-Hakim's elder brother Mohammed Baqir in the Shiite holy city of Najaf.