Updated

The U.S. military has arrested a "senior leader" in the network run by Jordanian terror mastermind Abu Musab al-Zarqawi (search), along with five others during overnight raids in the insurgent stronghold of Fallujah (search), officials said Saturday.

American forces have stepped up operations in Fallujah in a bid to root out al-Zarqawi's terror group, Tawhid and Jihad, which is believed to operate from there. The group has been blamed in numerous suicide bombings and beheadings of foreign hostages, including recent twin blasts inside Baghdad's Green Zone, which houses the U.S and Iraqi leadership.

The 1:30 a.m. raid in southern Fallujah targeted a site being used as a safe haven by al-Zarqawi's inner circle, according to a military statement.

Intelligence sources said the man captured was previously thought to be a relatively minor member of the terror network. But because so many of al-Zarqawi's associates have been captured or killed, he moved up to take a more important role.