There is described a washing machine configured to wash empty containers adapted to be filled with a pourable product, the washing machine includes: a conveyor device configured to convey a plurality of containers along a washing path in an advancement direction; at least one tank for holding a cleaning medium, the washing path extending within and along the tank; and a hollow passage which extends through the tank and which is fluidly isolated from the tank. The washing machine further includes a pair of extraction devices arranged in fluid communication with the tank, fluidly isolated from the hollow passage, and configured for detaching/removing labels from the containers advanced in the tank and for receiving the detached/removed labels, thereby extracting such labels from the tank.