Iraqi security officials say mortar attacks have killed five people and wounded 15 others in Fallujah, west of Baghdad.

Officials say the mortar rounds Wednesday apparently targeted a U.S. military base, but landed in residential areas instead.

In Baghdad's mainly Shi'ite Sadr City neighborhood, coalition forces detained six suspects believed to be members of a cell importing roadside bombs and weapons from Iran.

Separately, gunmen killed a journalist in the southern city of Amarah.  Authorities also announced that gunmen killed a journalism professor and his family in Fallujah two days ago.

Also Wednesday, Iraq's Foreign Minister Hoshyar Zebari said the abduction of five British citizens in Baghdad Tuesday was most likely the work of the Shi'ite Mahdi Army militia, probably assisted by local police.

Meanwhile, coalition forces handed over security responsibilities for three Iraqi provinces in the northern Kurdish region to Iraqi authorities.

The transfer of Dahuk, Irbil and Sulaymaniyah provinces to the autonomous Kurdish Regional Government will mark the handover of seven of Iraq's 18 provinces to Iraqi control.

Other provinces already handed over are Najaf, Muthanna, Dhi Qar and Maysan - all in southern Iraq.

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