Police in Belgium have made 12 arrests in a huge anti-terror operation, following the deadly bomb attacks on capital Brussels in March.Those detained on Friday night are suspected of plotting a terrorist attack, prosecutors said on Saturday. They were among 40 taken in for questioning, BBC reported.Searches were conducted in 16 municipalities, mainly around Brussels, with checks on 152 lock-up garages.On March 22, bombs killed 32 people at Brussels Airport in Zaventem, and one at Maalbeek metro station in the capital city.