Factbox: Why are Afghan night raids under fire?

KABUL (Reuters) - The growing use of "night raids" by NATO-led and Afghan forces to kill or capture insurgents came under fire from Afghan President Hazim Karzai this week, but the United States defended them as an effective weapon.

Here are some facts and figures about the raids, which likely will be discussed when NATO leaders meet in Lisbon this week:

HOW AND WHEN RAIDS ARE CONDUCTED

* U.S. special operations troops and Afghan forces typically surround a compound they think is being used by suspected militants from the Taliban or the al Qaeda-linked Haqqani network. Most of the raids are in the volatile south and east.

* Afghan troops generally use a bullhorn to urge those inside to come out peacefully or tell residents to leave their houses, the NATO-led International Security Assistance Force (ISAF) says.

* Under engagement rules tightened in 2009 and again this year, Afghan troops usually then enter first. If found, suspects are detained and weapons seized or destroyed.

* Raids are approved in advance by Afghan security officials, according to an ISAF official. More than 80 percent are conducted without a shot fired.

NUMBER OF RAIDS, ARRESTS, DEATHS

* Special forces carried out 1,572 raids in the 90 days up to November 11, or about 17 a day, according to an ISAF official. The pace is up significantly in the past five months.

* During the 90-day period, 368 insurgent leaders were killed or captured. Among lower-level cadres, 968 were killed and 2,477 captured, according to ISAF.

* More than half of operations result in the capture or killing of the targeted insurgent, the ISAF official said.

* Search and seizure operations -- mostly night raids -- killed 41 civilians in 13 raids documented in the first half of 2010, or 18 percent of the total killed by allied or government forces, according to a U.N. human rights report in August. The figure is likely higher given a lack of information, it said.

WHY RAIDS ARE CONDUCTED

* Allied officials say the raids disrupt Taliban and Haqqani insurgents and limit their freedom of movement at night.

* The role of night raids changed in July 2009 when General Stanley McChrystal, then-commander of U.S. and NATO forces, declared a new strategy based on gaining the support of Afghan communities.

* Along with a reduction in air strikes, he ordered that Afghan forces always accompany U.S. troops when they enter Afghan houses and there be greater sensitivity to local customs.

* The raids are part of the guidance General David Petraeus, McChrystal's successor, laid out in August: "Get our teeth into the insurgents and don't let go."

WHY AFGHANS COMPLAIN

* Afghans accuse troops of abusing residents, destroying property, insulting women, and acting on bad intelligence or based on personal vendettas, the U.N. report said.

* Afghans also complain that they often do not know which security forces carry out the raids, cannot get compensation for damage and do not know where detainees are taken.

* A report by the Open Society Institute and Afghanistan's Liaison Office on 2009 raids said detainees often were turned over to Afghan security forces, which are plagued by corruption and allegations of torture and other mistreatment.

KARZAI'S CRITICISM AND REACTION

* Karzai said in an interview with The Washington Post published on Sunday that he wanted the U.S. military to reduce its visibility and the intensity of its operations and end night raids. The raids "have to go away," he said.

* U.S. Secretary of State Hillary Clinton defended targeting "high-value insurgents" as a key part of U.S. operations.

* Petraeus also warned Afghan officials that Karzai's criticism of U.S. strategy seriously undermined the war effort, The Washington Post quoted unidentified officials as saying on Tuesday.

Editing by Paul Tait and Ron Popeski)