The U.S. military says it has killed eight suspected terrorists and captured 22 others in operations to disrupt al-Qaida networks in northern and central Iraq.

A military statement says the operations took place Friday and Thursday.  It says one of the detainees was an alleged senior al-Qaida leader in Sharqat, near the northern city of Mosul.

A separate statement says an alleged Shi'ite militia leader and three other suspects were captured in the Mashru area, south of Baghdad.

The military says the main suspect is believed to be a "special groups" leader and was reported to be linked to senior criminal leaders involved in attacks on Iraqi security and coalition forces. 

The U.S. military uses the term "special groups" to describe Shi'ite militias allegedly backed by Iran that have broken ranks with the Mahdi Army of radical Shi'ite cleric Moqtada al-Sadr.

A unilateral six-month cease-fire called by al-Sadr last August is due to expire at the end of this month.

U.S. commanders say the truce is a major factor behind a 60 percent drop in violent attacks in Iraq since June.  They also say they will continue to target rogue Mahdi Army units that refuse to follow al-Sadr's truce.

A report issued by the International Crisis Group this week says heightened pressure from the U.S. military on the Mahdi Army is likely to trigger fierce resistance in Baghdad and escalate tensions among Shi'ites in the south.

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