Norwegian , British vessels on World Food Program patrol prevent hijacking of Norwegian ship . Pirates captured after 6 p.m. chase , but then released , NATO says . Lacking formal procedure , NATO generally takes pirates ' weapons but lets them go . Saturday attack latest in a long string of hijackings and attempts in the Horn of Africa .
Canadian , British vessels on NATO patrol prevent hijacking of Norwegian ship . Pirates captured after seven-hour chase , but then released , NATO says . Lacking formal procedure , NATO generally takes pirates ' weapons but lets them go . Sunday attack latest in a long string of hijackings and attempts in Gulf of Aden .