Abu Musab al-Zarqawi, the man blamed for some of the bloodiest insurgent attacks in Iraq, has been wounded, according to a militant website.
Zarqawi is believed to be the most ruthless US foe in Iraq
The militant group Al-Qaeda in Iraq did not give any further details, but urged Muslims to pray for his recovery.
Jordanian-born Zarqawi has claimed scores of attacks against civilians and the security forces, as well as the kidnapping and beheading of foreigners.
The authenticity of the statement could not be verified.
US military officials in Iraq were also unable to confirm the report.
Zarqawi is the most wanted suspect in Iraq and has a US bounty of $25m on his head.
"O nation of Islam... Pray for the healing of our Sheikh Abu Musab al-Zarqawi from an injury he suffered in the path of God," said the statement in the name of his group's information department.
The statement said the injury was a reason to increase attacks on "the enemies of God".
BBC security correspondent Gordon Corera says the language of the statement is consistent with previous messages from Zarqawi followers, but does not appear in the group's normal website.
There have been unconfirmed reports that Zarqawi might have been injured, our correspondent says, possibly during a sweep of the Iraq-Syria border by US marines a few weeks ago.
The US military said it captured his driver at a checkpoint in western Iraq in February, but narrowly missed their main target.