Al-Qaida in Iraq vowed Sunday to carry out "major attacks" after the death of leader Abu Musab al-Zarqawi, insisting in a Web statement that it was still powerful.

The statement did not name a successor to al-Zarqawi, who was killed in a U.S. airstrike last week. But it said the group's leadership "renews its allegiance" to al-Qaida leader Osama bin Laden.

It vowed "to prepare major attacks that will shake the enemy like an earthquake and rattle them out of sleep."

The authenticity of the statement could not be independently confirmed. It was posted on an Islamic militant Web forum where the group has posted statements in the past.