FACTBOX: Security developments in Iraq, Feb 5

(Reuters) - Following are security developments in Iraq at 2100 GMT on Tuesday.

* denotes new or updated items.

* SAMARRA - Iraqi police and members of a neighborhood police unit found a mass grave containing about 50 bodies in an area west of Samarra, 100 km (60 miles) north of Baghdad, police said. Security forces had been searching for al Qaeda fighters when they found a house with 10 people inside who had been kidnapped from the area. Some of those inside led police to the grave. Three car bombs were also found.

* KHALIS - Six suspected militants were killed during operations by U.S. forces targeting al Qaeda near Khalis, 80 km (50 miles) north of Baghdad. Three died when one of the suspected militants detonated a vest packed with explosives. Another three were killed by U.S. soldiers in a nearby building.

BAGHDAD - One member of a neighborhood police unit and a civilian were killed by a suicide bomber close to an internet cafe at Taji, 20 km (12 miles) north of Baghdad, a local tribal leader said.

TIKRIT - U.S. forces killed two men and a woman and wounded a girl when they came under small-arms fire during raids against al Qaeda near Tikrit, 175 km (110 miles) north of Baghdad, the U.S. military said.

BAGHDAD - U.S. forces arrested eight suspected Sunni Arab militants during operations on Friday and Saturday in southern Baghdad, the U.S. military said.

BAGHDAD - Suspected Shi'ite militants kidnapped three Iraqi national police officers from a police checkpoint on Saturday in northern Baghdad's Ur district but released them hours later, the U.S. military said.

TAL AFAR - Iraqi security forces and U.S. troops killed three suspected al Qaeda gunmen during operations near Tal Afar, 420 km (260 miles) northwest of Baghdad, on Friday, the U.S. military said.