The fake version doesn't contain the drug's key active ingredient, which is given intravenously to treat colon, lung, kidney and brain tumours.
Roche, the drug's manufacturer, says it doesn't know the extent of the problem, or how the counterfeit versions were allowed to circulate.
America's drug regulator, the Food and Drug Administration (FDA), says the counterfeit versions don't have the name 'Genentech' on the packaging - Genentech is the Roche subsidiary responsible for the production of the drug - and could be part of batches numbered B86017, B6011 and B6010, supplied by Quality Specialty Products or Montana Health Care Solutions.
Avastin generates around $6bn sales each year.
(Sources; FDA website; Al Jazeera TV, February 15, 2012).