The present invention relates to a container lock, a method for locking a container with at least one door (2), and a container provided with a lock, said door (2) having a first frame edge portion (4), and said container having a second frame edge portion (5) positioned adjacent to said first frame edge portion (4) in a closed position of the door, wherein said container lock comprises: an interior blocking portion (6), having a body (20) adapted to extend over said first and second frame edge portions (4, 5), and an engaging abutment (7, 47, 87, 107) and an extension portion (8, 88, 108) extending out from said body (20) so that, when said interior portion (6) is arranged on the inside of said second frame edge portion (5), said engaging abutment (7, 47, 87, 107) and extension portion (8, 88, 108) provide interacting engagement of opposite side surfaces of said second frame edge portion (5), and said extension portion (8, 88, 108) extends from the interior of the container to the exterior of the container, and an exterior blocking means (9) for lockable interaction with said extension portion (8, 88, 108).