If it's a self-defrosting model, you should find, after thoroughly defrosting and removing the ice from the drawer, a drain hole, probably near the back.
This hole is where the melted ice water drains during the defrosting cycle. It normally (at least here in the U.S.) drains into a shallow pan under the fridge. It normally evaporates out of there due to the warm air from the fridge compressor, but on doingso, leaves a gunky mess that you should clean occasionally to prohibit unique and strange odors...
At any rate check to see that this drain is clear... it may need rinsing out with warm water or even running a small wire, such as a straightened wire clothes hangar down it to clear...